I think the reason why it happens is that very few people are actual heroes. More often, one persons very personal goal just happen to align with a larger group’s other goals and the group think that person is fighting their cause.
I think this is most painfully the case with Aung San Suu Kyi, the State Counsellor of Myanmar. I am old enough to remember when she was awarded the Nobel Peace Prize in 1991. Today, she is the leader of a government that has participated in an attempted genocide and routinely jails people trying to expose it.
Maybe the Nobel Peace Prize should be awarded posthumously?