At least after 15 years he has accomplished SOMETHING.
I know of a guy that ended up buying his neighbors house just to set up a model rail road. It is an amazing RR track and village, but in the end the trains just go round and round, and other guys have a bigger and better model RR setup.
To dig a basement with all RC models is at least doing something productive. Very slowly, but productive. I still think he is a little nuts however.
I have been working on my 911 for 16 years and it still have some projects left to do.