@Darklight99
None, because if the genders was reversed you all would see the MC as a victim of the circumstances. He is still a victim of this as long as the blackmail still stands.
@xyzzy
To be fair, MC could frame it as paying to adopt the kids and thus escaping the act of 'buying them as slaves'. Even if the end result is the same, the meaning of the act is different provided that he doesn't treat the kids as slaves.
@twinklecake
To be quite honest, Logically the greatest happiness a slave can have is 'not being a slave' but then they wouldn't be a slave anymore so that wouldn't really be a possibility.
So the greatest happiness a slave can have while still being a slave would in fact be 'Having a good master'.
@monkey123
And that is very likely the reason he decided to refrain from going deep with social relationships, can't get backstabbed if you don't present your back to others.
If anything, this is a pretty good depiction of how deeply betrayal cuts. The closer the bonds, the deeper the cut will be and it will affect every social relation that follows. It's not a matter of 'lol just try again at the next school' when his entire look on social relations has been...
To be fair, given that they are still in elementary, dude has likely not entered puberty yet and doesn't have the chemical interference that comes with that. So he's not really a chad and just is really outgoing and friendly.