Guy became a Vtuber, obsessed over it so much he became his avatar, hence title "incarnation". Most likely streamed himself to death too. Then when the pov character enters the appartment, he gets dragged into the rabbithole too and starts the cycle again. Essentially a digiage version of The Grudge and haunted doll stories.
Might be the shock of entering an apartment, with whose residents, you've been having issues only to find it empty aside from a single laptop on the floor... I think that would kinda short-circuit your brain...So guy is so mad that he's willing to cuss the guy out..but not just bash the laptop? Come on, I know guys with who got interrupted of sleep ONE time and start going on a rampage
the downside is you won't be able to enjoy the superchat moneyGet digitized into a cute anime girl by a haunted laptop? What is the down side again?
This could very well be a premise of some LN.