Benjamin Franklin said: "Our Constitution was made only for a moral and religious people. It is wholly inadequate to the government of any other."
In other words, something noble like the Constitution only works for decent human beings who have a conscience.
It does not and cannot work for evil, psychopathic criminals who have absolutely no conscience, because they will utterly ignore it and do whatever they want.
The United State Consitution, much like the Ten Commandments, is simply a set of guidelines for decent people who want a better life. There's nothing inherently in it to force anyone to behave, so the psychopaths don't.
It's up to the rest of us to deal with them.
Has psychopathy become more prevalent? I don’t think so. People can always be counted on to pursue their personal interests before anything else. The founders built checks and balances into the system to correct for “the crooked timber of humanity” but they’ve been effectively neutralized.