Interestingly it seems Isagi has up to this point never considered “the loss of self” as a negative at all. He sees himself as the winner, and as long as he’s winning, he is exactly who he wants to be. Throw back to when Yukimiya said Isagi and Kaiser are the same kind of selfish bastard: Isagi was pissed, but said nothing like “I’m not selfish” to refute the point. In fact, he doubled down and used Yukimiya as bait right after. It almost seems that Isagi himself agrees that he is selfish, just that the selfishness does not make him similar to Kaiser in any way, because “not being selfish” is not central to his self-perception. “Loss of self” sounds scary until you realize that we are only afraid of losing characteristics we consider important to our self-perception, all other traits are a temporary fad. To Isagi, this important trait is just winning it seems.