He's not. No radical people are practical, it goes with the job of being radical.
rms wants you to write code for free, give it away for free and never ask for any money if anyone uses it. It's anything but practical. It's not even realistic.
He was lucky to be at the right place and the right time where this kind of delusional ideology could actually work (because nobody had this idea before him). Good for him, and he's reaping the benefit of getting there first (basically living off speaker fees). But he totally fails to realize that nobody else can do this.
I respect what he did for the software industry, but personally, I think he's a lunatic, a bit like your crazy grandpa that you quietly wheel over in the kitchen when there are guests so he doesn't make them run away.