It's not the environment that matters, it's the change of environment. Switching things around gives you a reset button. Over a few years in a particular life circumstance, you usually learn a lot about what you want in life. But you also acquire a lot of inertia and old habits. A move, new job, and new social circle gives you a reset button that you can use to pick up a new set of habits.

Of course, it's up to you to actually press that reset button.

One of the best things I ever did with my life was to found my own company. The company failed - it just petered out and never went anywhere. But it got me off the "Java developer for a small financial firm" track, helped me learn a whole bunch of new skills, and those skills got me a job all the way across the company.