It's been a while since I watched the movie but I never got the impression that her father needed extra caring for. He fell ill towards the middle of the movie but was healthy in the beginning IIRC.

Our introduction to him is an invention backfiring and harming him non life threateningly.

I get the impression that without Belle to mind him, he would be dead from an invention that went too wrong, though it is not explicitly stated.

He falls ill after the townsfolk imprison him without heat in winter. Their excuse for locking him up is "he's crazy" when he tells them of the castle and it's inhabitants.

I agree that learning and thinking are incredibly useful to society, but only if that knowledge gets applied somehow.

She helped her father. Without her encouragement, he would've given up, but he kept at it and finished the wood chopping machine. And it's implied that he wasn't really caring for himself. I'm not sure if he did anything else like farm, or maybe he was an aging woodchopper looking to find a way to keep being useful.

Belle was more than able to be an educator but it seems like she was completely disconnected from everyone and chose to spend all of her time on leisure.

How do you educate a town that doesn't want to be educated? And again, she was self-educating in her spare time. It's unreasonable to expect every hobby to be expressly for helping others, just as it would be to monetize them. Not to mention, education is an investment. Maybe she could invent something in the future like her father was doing in his later years. More likely is that she might write books of her own, but you see how little the rest of the town values books and those who read them. The town just isn't the right place for her.

It's weird that the town gave a shit about her choosing to read, and even weirder that people here in the real world are siding with the fictional dumb hicks here. It's not like she owed them anything. Especially after the way they treat her and her father. Fuck those judgy yokels. Even these days, I get a sour look when I mention reading books. It's like half the people in the world decided to grow up to be Matilda's shitty parents.