Playing in public engenders new paths in your brain that you won't get playing alone. In other words, I can learn something playing in public in five seconds. If I was learning it in private, it might take me three months to get.
I guess fortunate that I'm still around and I emphasize I guess because you never can tell what musicians would be playing had they been around as long as I have.
I am always happy to be practicing. Period, ... I enjoy just playing my horn and going into the type of meditation that playing involves. It puts me mentally in a place that is always transcendent and above real life. I love playing just for myself. It's a great experience.