I always wondered how restaurants even work - how can owners be motivated to keep themselves in this endless, poorly paid grind. In my opinion, when this is not about large chains that are effectively self-reproducing machines that don't depend on any people's motivation, it's mostly either hobbies (someone runs it to keep himself busy and feel beneficial to the society during retirement, for example), or just failures (someone foolishly believes there's a massive amount amount of money to make, gets burned, and vacates the space to leave it to the next one). Yours truly have been that sort of person in my younger years (when it was a lot easier, as industry professionals say!).
And yes, i can easily understand how can one become a dick being a restaurant owner. You deal with people who are paid poverty wages (there is no choice here), who can't be motivated with anything but threat of losing their jobs, have no work ethic (or they'd be doing something better), and in general can't be trusted in anything at all. You become paranoid and you quickly learn to disrespect people. I can feel that guy, don't judge him so heavily.
This is a hellish business to do and anyone who envies them is a fool.