Is there any mathematician who felt guilty for one of his math discoveries ever? Quoted from Wikipedia:


  In 1888 Alfred Nobel's brother Ludvig died while visiting Cannes and a French newspaper erroneously published Alfred's obituary. It condemned him for his invention of dynamite and is said to have brought about his decision to leave a better legacy after his death. The obituary stated, Le marchand de la mort est mort ("The merchant of death is dead") and went on to say, "Dr. Alfred Nobel, who became rich by finding ways to kill more people faster than ever before, died yesterday." Alfred was disappointed with what he read and concerned with how he would be remembered.


Alfred Nobel felt guilty for invention of dynamite. He shares this emotion with many other scientists of the human history who became disappointed when they realized that their discoveries make the world a worse place to live. But what about mathematicians? We know almost all scientific discoveries are based on mathematical theorems and concepts but it seems feeling guilty is much more epidemic amongst physicists, chemists and biologists rather than mathematicians. 


  Question: Is there any mathematician who felt guilty for one of his math discoveries ever? If yes, what was that particular theorem or concept? Please introduce historical references and other quotations which confirm existence of such an emotion.
Einstein, while not strictly a mathematician, expressed profound regrets later in his life when he pondered on the possibility of an atomic war. In 1939, he wrote to Roosevelt to urge the Americans to develop the atomic bomb before Germany, and Roosevelt took action as a direct result of this letter. In 1954, in an interview to The Reporter, Einstein said:

If I would be a young man again and had to decide how to make my
living, I would not try to become a scientist or scholar or teacher. I
would rather choose to be a plumber or a peddler in the hope to find
that modest degree of independence still available under present
circumstances.

(He is often credited to have said: &quot;If only I had known, I should have become a watch-maker.&quot; But it appears that he never said those exact words.)
I've heard apocryphal stories that Newton was reticent to publish his calculus, concerned that the human race couldn't handle the power.  He only begin publicizing it when Leibniz started publishing prolifically, about 20 years later.  Perhaps somebody has a citation; I don't, hence I consider it apocryphal.