They were talking about MC getting paid a lot of rewards, but what's the reward? Money? Is money really that valuable, with them still being imprisoned and all? Shouldn't he be finding a way to be free instead?
What about his classmates, who are still suffering? Can't he at least make them have more leeway?
Comfort and freedom are pretty different things tbh, and considering the MC's attitude (just wanting to fuck all the time) I assume he cares more about comfort. Even if the chancellor sucks morally, it's a beneficial relationship to him because the chancellor has both money and the power to get things done, which would be harder for him to do if he just escaped and became some random peasant. In return he just has to do what amounts to him as menial chores, so it's a pretty good deal.
In name they're still slaves, but if he plays ball with the chancellor I could easily see him getting a mansion/concubines/whatever. He's about as restrained as a rottweiler on a leash held by a 5 year old, everyone knows that if he wanted the MC could kill the chancellor easily, but he gets more out of the situation by playing along.
Does it make him an asshole for ignoring his classmates though? Absolutely, but I don't think he cares, from what we've seen of his disinterest in anyone aside from his partner in general.