This would have deeply weird and counterproductive effects on election candidacies; ultimately, people are willing to do their duty for the country, but not at the expense of their entire future income growth. It's the constituents' job to vote for better candidates, there are no foolproof rules beyond that.
i think you underestimate how many silent heroes and patriots walk among us
in the end , the people running for office should decide if its a price they are willing to pay
it used to be a celebrated virtue to be a company man. why cant it be the same to be a "government" man ?