I usually answer "why would anyone do anything else"....When we started trading on the Options Floor in the 1970"s, no one even knew what a "market maker" was (not much fun at cocktail parties!). The independence is cool, but I think that playing the game is the biggest motivator for most. Being able to compete in the highest level financial arena available is what gets me up every morning. Very few of us can compete in major league sports, or the olympics, but we can play in the big leauges here.
When I first started trading (and lost some money), my brother told me that everything is different now...we are in tthe "big leagues" - and if we were able to continue playing, then we would eventually win .....and winning is simply being able to play everyday..
Enough philosophising, back to the orignial..."why would anyone do anything else?"