It's not the boosting or the immunities that make Xinchub valuable. It's the fact that he's functionally immortal.
Most of you people live for maybe a century before your brain just gives up and you die.
Xinchub's brain is different now. It isn't going to give up, and he can't be killed.
Oh, I bet I could kill him.
In order to prove you right we have to not get paid.
But right now I don't want to.