But the thermo ones tended to just drop out of ME and go to civil or industrial
Well, you have to take thermo as part of civil, too. However, it's an easier thermo. Same with dynamics.
I made it all the way to instrumentation & heat transfer before I switched to civil. I was doing fine in ME; I just had a change of heart. I know that I could be making more money in ME, but I don't think I'd be happy. I love what I do everyday. I also work with MEs a lot, and have a very good idea of what they do. Just don't think I'd want to do it everyday. I enjoy the large scale of my projects.