Western media is reporting this in a heavily slanted way, as if he's just some guy who 'donated' money when it wasn't, she scammed him (proven, in court). So the real story is:
Ai Mogami (Airi Sato) was the Japanese Sliker. A pretty popular streamer who averaged around 6,000 viewers and enjoyed privately messaging her fans making up wild reasons for why she needed to borrow money. She eventually ended up scamming a legitimately schizophrenic guy into borrowing money from loan services by convincing him of such things as her sister being sold into sexual slavery if he won't.
The guy eventually ran out of options of pushing off repayment to the loan companies, asked her if she could start paying him back even just $100, she said she would start paying back in 2 days, then blocked him.
He took her to court and easily won the court case. Judge ordered her to repay him back around $40,000 US. She ignored the order to pay him back. He'd go to police about it and they would say that they "couldn't find her" (Japanese police are notoriously useless, lived there for years) despite her streaming every day and him showing the police where she was.
What finally snapped him into doing it was she started making snide comments about him on stream.
Here's a good video going over most of it. Crazy bitch deserved every one of those stabs and most Japanese commenters I've seen posting about it are based enough to say the same.