Rowling is a bigot and her work is as derivative as it gets. But she did work hard writing, and she was extremely lucky that her books became so popular. Thousands of excellent books are published every year that are just as good or better and they don't catch on the way the HP series did.

All of those things can be true at the same time, and it's not crab mentality to point them out.

The lessons to be learned here are this:

Keep writing. Until your ideas are on paper, they are just ideas.

Don't be discouraged by a lack of success. If your writing doesn't sell, doesn't immediately capture hearts or resonate with the masses, this doesn't mean it isn't good or worthwhile. Write for yourself. This was the point that JK was trying to make, I think.

Success requires help. Nobody does it alone. JK would absolutely be nobody without editors and publishers and marketing helping her books reach an audience. Find people that share your vision and support your dreams. Aspiration is good, and expectation is counterproductive.

Be excellent to each other. Rowling is a bigot, and that's part of her legacy. But she's just an author. She's not an authority, she's not a leader, and she's not a role model. Don't be a bigot. It will improve your writing, but that's a tangential benefit of being a good person.