I have never found this to be a satisfying explanation for the mass betrayal we see again and again from so-called Conservative Republicans.
In 2014, more than 50% of newly elected Congress people were millionaires BEFORE they got to Washington D.C.
If wealthy candidates were just interested in money, the most sensible thing to do would have been to stay home and continue to focus on the private career that already made you wealthy.
Once they get there politicians don't want to leave.
And a million dollars doesn't go that far in DC.