Why are all these Senators and Congressmen deciding to retire or not to run for re-election?

I'm going to take a wild guess that it has to do with money. These inbents know that if they lose their bids for reelection they will be in debt to their campaign contributors. Since they also know they don't have a snowball's chance in hell of winning, why run at all? Better to bow out gracefully and never have the stigma of losing an election attached to their name. They can still work in government or the private sector and earn a good living, and they will never be asked why they think their opponent made mincemeat out of them at the polls. And of course whether they choose to work again or not, they still get their government benefits for life. Yes, it's unfortunate we have to pay for this, but we will never again have to put up with their voting habits. It's a win/win, for us and for them. How American.