Wouldn't they have to prove Phil was specifically using it for business? I was always under the impression if something is used outside of your business, you can't claim it. For example, a streamer wouldn't be able to claim a new computer as a business expense if they also used it outside of streaming for personal stuff.
It does become murkier with Phil because I can't think of the last game he streamed that he played outside of Twitch, I just don't know how the IRS would reasonably prove something like that, or how you'd really report that as fraud. It's not like Phil is drowning in gifted games, I was always under the impression he preorders most of his stuff (sometimes twice) and only really gets gifts when he refuses to play a game people want him to play. I know the IRS can be hard asses, but I can't imagine they'd launch a full investigation on Phil not reporting a possible $200 or something in business income, especially if he's reporting the bulk of his income, which is likely still around 100k. Then again, this is Phil, so if he was under investigation I know he'd find a way to shoot himself on the foot and confess to doing something way shadier because he's his own worst enemy.
I'd compare it to fellow online cow Onision, who did get in serious trouble because he straight up tried to write off everything in his life, like his entire house because he makes vlogs in it. I am by no means trying to defend Phil or anything, I just think we have plenty of examples of him legitimately scamming people that we don't need to go digging for more. I mean, it hasn't even been a month since the "emergency tax fundraiser" that just so happened to totally naturally occur around the same time Phil took a vacation and got married.