Some restaurants do awesome. But I was just reading something about 50% of restaurants failing within the first year. And a lot of it, ime, has not been due to shitty food or service, but due to inefficiency and miscalculations - you have to dump a bunch of produce, it's money down the drain. You sell out of your special too quickly? Also money down the drain. Too many servers on a slow night? Money down the drain. Not enough servers on a busy night, and the queue is too long, so patrons leave? Money down the drain.
Same with stores. I know small retailers who built out their own space, and didn't take a single day off, for 24 months, or hire any additional help, to just start to make a profit. And these were were guys who had been around the business for a long time, had extensive customer lists, and so on.