On the plus side, learning to disregard resentful negative people is an important life skill and parent is helping teach it.

It's far better to be positive. For example a good friend of mine founded a successful crypto shop. At the time, I thought the idea was stupid. However I didn't say that, I told him I wanted him to succeed and I was happy to listen to him describing what he wanted to do and how he was going to do it. Now our friendship is even closer and he's doing great. While it's unlikely given his personality, if I had been negative I might have talked him out of a big success and that isn't what good people do.