NSA Mass Spying has stopped zero terror plots so why has the Senate voted to continue to fund it? Updated 12/11

The Senate has just voted to continue to fund NSA Mass Surveillance and also to fund a witch hunt on any NSA leakers.
http://rt.com/usa/senate-intelligence-act-approve-319/#.UnyPOrDu1y4.twitter

Keith Alexander has already admitted, in sworn testimony to Congress, that NSA Mass Surveillance has not foiled a single terror plot in 12 years since 9/11.
So well over $100bn has been spent and not a single terrorist plot has been foiled that could not of been foiled via pre Patriot Act laws, by obtaining a warrant after finding probable cause.
http://www.allgov.com/news/controversies/nsa-director-alexander-admits-he-lied-about-phone-surveillance-stopping-54-terror-plots-131007?news=851326

NSA Director Keith Alexander admits he outright lied to Congress about the 54 terror plots.
He now admits that, at most, only one or two terror plots were foiled by Mass Surveillance.
The true number is probably MINUS ONE.
Because of the systems in place and resources diverted to spying on law abiding citizens, the NSA failed to stop Boston.

So we have to ask the question :-

If NSA Mass Surveillance does nothing to keep Americans safer, indeed the evidence is that it makes Americans LESS safe, what possible reason could the Senators that voted to continue to waste tens of billions of dollars on a program that has singularly failed to fulfill it's official purpose?

Answer
The official explanation - counter terrorism, cannot be the reason the Senators voted to continue it, instead of voting to DEFUND it.

Some possible reasons :-

Bribery and Corruption 
Some of the Senators will have been bribed with campaign contributions (and/or other inducements) by the private contractors that work for the NSA - contractors like Booz Allen. 
75% of NSA funding and 75% of the staffing, goes to private companies who profit from the Mass Surveillance programs.

Blackmail and Intimidation
A significant proportion of the Senators, that voted to continue funding, will have some secrets that they would rather be kept hidden from the public.
The NSA (with the help of agencies like the CIA, FBI and DHS) could easily obtain at least some of this information and threaten to leak it to the mainstream media, thus wrecking the Senators re-election prospects as a minimum.

Hoover was well known for keeping detailed surveillance records on every prominent politician and many other prominent people in order to intimidate and/or blackmail them.

He used the FBI to harass political dissenters and activists, to amass secret files on political leaders,^[2] and to collect evidence using illegal methods.^[3] Hoover consequently amassed a great deal of power and was in a position to intimidate and threaten sitting Presidents.^[4]According to President Harry S. Truman, Hoover transformed the FBI into his private secret police force; Truman stated that "we want no Gestapo or secret police. FBI is tending in that direction. They are dabbling in sex-life scandals and plain blackmail. J. Edgar Hoover would give his right eye to take over, and all congressmen and senators are afraid of him".  
https://en.wikipedia.org/wiki/J._Edgar_Hoover 

Why wouldn't Keith Alexander and/or James Clapper want to amass the sort of power that Hoover enjoyed during his long tenure as head of the FBI?

We already know, from testimony from Russ Tice (an intelligence whistle blower), that the NSA secretly spied upon Barack Obama when he was campaigning to be the Senator for Illinois in 2004.
http://www.huffingtonpost.com/2013/06/20/russ-tice-nsa-obama_n_3473538.html
What information might the NSA have on Obama?
Further details or evidence on this, which has not been released by the mainstream media?
http://ian56.blogspot.com/2013/01/what-has-john-brennan-got-on-obama.html

Disparaging information on Obama, not yet widely known in the public domain, would certainly explain why Obama has not prosecuted, or at the very least fired, both Clapper and Alexander for perjury (multiple counts of lying to Congress).
Perjuries which they have both now admitted. 

We already know that John Brennan secretly spied upon Barack Obama during his 2008 Presidential campaign (see above link).

Secretive information held by Brennan on Obama would certainly explain why Obama came to appoint Brennan as his National Security Advisor, Drone Policy and Kill List czar, and later Director of the CIA.
Brennan is :-
a known advocate of torture from the Bush regime
a total failure in his previous CIA roles - See this
the appointment of Brennan as CIA chief, with his own fleet of drones, despite Brennan's drone warfare program being an absolute demonstrable failure (for it's official stated purpose) - See this,
and this

Advocates of a Police State and the undermining of democratic processes in America and the West
There are at least some Congressmen that advocate the further expansion of the Police State and Police State powers.
Two examples would be John McCain and Lindsey Graham who co-authored the 2011 NDAA Act that codified indefinite detention of American citizens and the effective repeal of Posse Comitatus which now allows the U.S. military to operate on the streets of American cities.
http://ian56.blogspot.com/2012/11/obamas-civil-rights-violations.html

The principal purpose of the NSA Mass Surveillance is undoubtedly not counter terrorism but to :-
further expand Police State powers
to crackdown on any future domestic political dissenters
to control prominent politicians, senior judges, senior government officials, prominent businessmen and other politically minded prominent people
to further erode what little remains of a Free Press in America (as opposed to Corporate controlled propaganda, distractions and omissions)
to intimidate the few real journalists left in America
to intimidate civil rights activists like the ACLU and EFF

In short the purpose of the NSA's Mass Surveillance is to completely undermine democratic processes in America and in the West - the same reason that the Stasi carried out their Mass Surveillance on their own population.
http://ian56.blogspot.com/2013/09/the-primary-purpose-of-nsas-mass.html

The Senators that voted to continue funding the Mass Surveillance programs with billions more taxpayer dollars and to launch a witch hunt for any further whistle blowers must of at least started to realize this.

Any Congressman that votes for the continuation of the NSA Mass Surveillance programs needs to be removed from office as quickly as possible.
The future of America and the principles of Constitutional governance and a democratic Republic, upon which America was founded, are at stake.

Update 12/11 
Someone else has the same thoughts as me
Is the NSA Blackmailing Its Overseers In Washington?
http://www.washingtonsblog.com/2013/12/nsa-blackmailing-overseers-washington.html 

How NSA Mass Surveillance is intended to be used for blackmail, intimidation and to discredit domestic political opponents
http://www.whizart.com/blog/2013/12/08/not-just-porn-nsa-targeted-academics-private-citizens-too/ 

Appendices 

James Clapper and Booz Allen - a tale of high level corruption
http://ian56.blogspot.com/2013/06/booze-allen-hamilton-what-you-dont-know.html

Addendum

Keith Alexander has his own reasons for keeping all of the NSA's Mass Surveillance powers.
Why wouldn't he want to be in a position of power that rivals, or perhaps even exceeds, the powers of the President or the Chairman of the Federal Reserve?
He certainly does not want to be sentenced to 75 years in jail -which is the sentence that could be imposed if he were convicted of his multiple counts of perjury to Congress which carry a maximum penalty of 5 years for each count.