Not sure which part you mean, but it happens relatively often yeah, like when people get "hacked", which is generally reusing passwords/having trojan of some sorts/forgetting to change your pass after you played at a "friend's" house and shit like that.
The result varies depending on which platform you get fucked on though. PSN is notoriously fucking shit at refunding stuff, and if you chargeback, they'll just close your shit no question asked and basically all you digital games are gone forever, even the ones you bought. That's even if it's fucking obvious that there was an issue cause all of a sudden you bought 300$ worth of games at once. The problem is even more insidious because a "hacker" can create a subaccount on your account and you can't refund anything on that because whatever fucking weird ass reasons. So quite often you'll get refunded A PART of what you spent, and still have to pay the rest if you want to use your account. Whole system is fucking shit, and anyone with a bit of info on you can sometimes get the PSN support to give them access, which is even more fucked. Definitely don't keep any form of automatic payment on PSN if you use it a lot(or at all really).
I don't know about Xbox, but I'd assume it's similar shit as PSN. Same for Blizzard I don't know how it works, however Blizzard has more complex security in general(authenticator, IP based verifications etc) and I don't think you can buy that much on a Bnet account anyway. Maybe WoW shit I guess. Also Bnet requires ID to do any account level modifications, so it's harder for anyone having access to your account to transfer ownership or whatever. On the other hand if you're a retard and typed random shit on your Bnet info and you get in trouble, you're not getting it back, so don't do that.
For Steam, it's A BIT better, in the sense that it has better security also, and they're usually pretty easy with the refunds(hell if the games aren't played you don't even need to contact support, although if you try to refund 300$ worth of games they might flag your account for some shit), however they'll sometimes fuck some shit up, and since it takes like 3-4weeks to get an answer to an email to their support, it takes fucking forever to have a back and forth to fix anything they might have fucked when reverting the account. So for Steam you better hope they don't fuck up, or your only solutions are literally emailing Gabe or trying to get Reddit sharpening their pitchforks which generally gets someone important to check it. Steam has easily the worst customer support of pretty much any online platform, even the shit like Uplay and Origin.