Plus the guy gets paid well. Why should he care about React?

You don't generally want (and really shouldn't) to be on the leading edge in a corporate setting.

The reason they don't is that is simply isn't needed in their work.

There is your answer. Most people want to have a job where if they are paid well and are reasonably safe, they don't care. I am not saying its a good or bad thing. It's just the way it is.

You cannot convince someone to pick up new things because YOU think thats what they should do. I personally think people should always be learning new things but I cannot expect my friend to do it if thats not what they think.