My general assumption for the lowest I can expect a person to behave is basically always looking for their own absolute gain, and any attitude towards other people comes secondary to that. So while a person living by this standard wouldn’t donate to charity without some other motive, they would have basically the same answer to something like the trolley problem as anyone else.

Am I wrong thinking of this as a “minimum reasonable behavior”, or is there something people actually gain from the suffering of other people?

This question was born out of seeing how people are being treated by the US government at the moment, but I’m asking about more than just that. People like abusive partners/family, hostile cops, or just bullies in general.