I've found that, nowadays, no one GOES INTO POLITICS to do anything but further their own agenda
I thought of adding examples but, that seemed a bit redundant, we all know them already
The only way to avoid this trap is to implement a sortition based representatives chamber/s, with a likewise selected head of state, pm, etc. You serve a limited time, you get no "reward" no bribes or "gifts" no 2nd term, a one time deal.
Imagine actually getting shit done! Wow that'd be novel!