As far as I'm concerned, the only one to blame for anything is Bobby himself because he's the one who put out videos "hating" on Shane that ultimately got the ball rolling. And Bobby didn't have to agree to do anything..
For all we know Shane could have been a douchebag of a boss but at the end of the day he flew Bobby to LA, gave him a place to live, bought him a car (which Bobby quickly wrecked) and handed him an audience of Millions once a week. People go into debt and share apartments with a bunch of people working as interns just hoping for opportunities in whatever field they're focusing on. Bobby was wanting to be a serious, successful YouTuber and he was just handed the ultimate opportunity to prove himself. And he couldn't handle it. And you have no business being a YouTuber if you can't handle online bullies. Especially if you're known for being one yourself.