Restaurants and grocery/convenience stores are a bit different. Yes, owners of both are signing up for long hours and poor pay. But the motivation is often different:

- if you buy or start a grocery store, you know you're buying yourself a job; you won't get rich, but you will make more money than you would working for someone else, e.g. if your options are limited due to discrimination, lack of fluency with local language, literacy etc.

- if you open a restaurant, you might me doing it for all the same reasons as above (think an undifferentiated Chinese restaurants, or a local pizza place). But many people open restaurants because they are into food, because they think the way they make food is better than existing restaurants, and because they think the margins are going to make the restaurant ultra-profitable.

(My parents also had a grocery store.)