This is true. I made the question a little broader, so it could speak to the interests of whoever decided to participate in this thread. Someone who is super-focused on career is not likely to be as concerned about looking like a pro-level bodybuilder (unless they are a pro-level bodybuilder). Working on a side-project- like a programming a computer game- tends to distract from other aspects of life, even if it's more a hobby than a business venture.
Or the flip side, having a successful career can create more opportunities to be involved in outside activities, i.e., if you're successful and have money, you may have to work less, and can spend more time being involved in outside activities. If you're working 4 jobs to just pay the bills, you will probably have no time for outside activities.
So, when you say you want to be the best in your career, does that mean you want to produce excellent work? Or does that mean that you want to be well-known nationally and internationally, establish your own firm worth $100s/millions or more, be profiled by Forbes, have books written about you?
I want to do excellent work and be well-know, both nationally and internationally (though, Id be just as happy with being nationally known). It is highly unlikely that form of recognition will produce $100s/millions. It may, but highly unlikely. So, its more about being nationally/internationally known, doing good work, and living comfortably. Obviously, I am not opposed to being wealthy (worth 300 million dollars), but it rarely ever happens in my line of work.