The fraction of people who get into politics (or want to climb the corporate ladder) who aren't largely motivated by self-interest, is, I would guess, small.

Oh but a judge can think ‘I would be good at that’ before becoming a judge and their judgement could be correct. Sotomayor is quite exceptional—and it would not be wrong for her to know it. But we still have the right to change the structure of government.

Yes, but I'd prefer someone whose judgement is admired by OTHERS than one who thinks that of themselves.

Being humble is a quality not often enough admired.