Why do sitting members of the National Assembly go out of their way to become Ministers?

It is difficult enough to get a nomination to become a member of the National Assembly, and even after getting nominated, winning the election is no easy feat. Yet, when they become a Minister, they and even their family members have their entire pasts exposed during confirmation hearings, facing public humiliation. Even after being appointed, they are relentlessly grilled by members of the National Assembly. Is the position of Minister really that meritorious that it's worth it just to get through those brief moments???
Honestly, I don't quite understand it........