i think he cared when he started the restaurant/at the start of the show, he wouldn't be so protective of the formula and spongebob if he didn't care.
when the writers stopped caring, he stopped caring and sold him for 62 cents, fired him for a nickel, started serving grease on a plate and started serving patties that turned yellow.
thankfully, sponge on the run brought him back to his senses and realized the value of spongebob and his skills and his love of the craft
(also i feel like sometimes, the writers use mr krabs as a way to represent the execs at nick, and spongebob to represent the artists)
(PS headcanon theory: when the krusty krab started, he was driven more by passion than by greed, because it wasn't as well known so he had to focus on making good food. but when it became a huge hit, the money got to his head and he forgot the reason why he started.
kind of reflects the show itself, it started modestly but then became a money making monster that pumps out sequels and spin offs every week. sure, maybe the artists[SpongeBob] care, but do the higher ups[Mr Krabs]?)
I think deep down he really does care, but the allure of money distracts him, and sometimes he has to be reminded why he loves his restaurant to begin with
he's actually one of the most interesting characters for this very reason