Well, a few people have touched on this, but it seems to me that the biggest reason professional athletes do their sports is because of where they have the most talent. 99.99% (or more) of the population does not have the physical ability to be an elite at any sport. If we take the universe of professional cyclists, how many have even the theoretical physical talent to be professional golfers? It's a question that can't be answered exactly, but it is not likely more than a handful. So essentially professional cyclists have no option to be professional golfers (although Nick Faldo was a pretty good cyclist I believe). Probably a number of professional cyclists could have been professional distance runners or X/C skiers if they started at a reasonably young age, but even there I bet most of them wouldn't have the exact physiology required.
Now, I guess the original question was about psychological makeup and what makes people choose different sports from a mental standpoint, and that implies something beyond pure physical talent. I bet most cyclists never tried very hard to be professional golfers and it wasn't because they'd tried it and found they were bad at it. But it just seems to me that phrasing the question to ask what psychological attributes cause people to choose cycling is ignoring that elephant in the room of natural physical tendencies.
A discussion specifically of differences in psychological makeup between say cyclists and golfers - leaving out the "why did they choose it" aspect - makes a lot more sense. And some others here have pointed out some very good thoughts on that. I know for me, even though I love playing golf and shooting hoops, my natural physical talent for endurance sports makes them feel special. not because I'm winning per se - in my prime I was a level or two below professional at running and racewalking and way below that at cycling - but I know that my natural ability make running and cycling, especially running and cycling hard, feel very different than they do for most people. So I believe that you can't separate the physical from the mental as much as one might think.
Now, I guess the original question was about psychological makeup and what makes people choose different sports from a mental standpoint, and that implies something beyond pure physical talent. I bet most cyclists never tried very hard to be professional golfers and it wasn't because they'd tried it and found they were bad at it. But it just seems to me that phrasing the question to ask what psychological attributes cause people to choose cycling is ignoring that elephant in the room of natural physical tendencies.
A discussion specifically of differences in psychological makeup between say cyclists and golfers - leaving out the "why did they choose it" aspect - makes a lot more sense. And some others here have pointed out some very good thoughts on that. I know for me, even though I love playing golf and shooting hoops, my natural physical talent for endurance sports makes them feel special. not because I'm winning per se - in my prime I was a level or two below professional at running and racewalking and way below that at cycling - but I know that my natural ability make running and cycling, especially running and cycling hard, feel very different than they do for most people. So I believe that you can't separate the physical from the mental as much as one might think.