This seems like a non-sequitor. If the original post had attributed the quote to Stephen Speilberg, would you have responded similarly? I doubt it. My point: It's a great quote and some good life philosophy to consider. It doesn't really matter who said it.
I think so. As a rule, the lives of celebrities are pretty fucked up when you get behind their public facade. I'm not saying anything specific about these two, as I don't know either of them. I guess I'd amend my comment to say don't take life advice from celebrities. Unless, perhaps, you aspire to be a celebrity.
The "be the hero of your own movie" advice is pretty cliche as well.
Don't take life advice from anyone. Evaluate who is successful (according to your definition of success), what they do with their time, how they think and act and speak, and do more of that. To most people, Joe Rogan is wildly successful. He says lots of things which are wrong, but he also does lots of things which have led to a very happy life. I would love to spend my days working out, smoking weed, speaking to interesting people, and being paid billions to do so.