Every driver, no matter what kind of series they run, has activities they do outside of the race track. Some have a regular job to help fund their teams, especially at the local level, while others at the top tiers have their own extracurricular activities.
These range from just playing ball sports, or doing things with their kids. Some go to the amusement park, while others get daring and go extreme by doing crazy sports, like sky diving or go rock crawling.
Truthfully, some drivers call their extracurricular activity as racing, it's just who they are.
Guys like Brad Keselowski, Kyle Busch, and others go to other tracks and other series to simply race because they love to do it. That's what they enjoy, and normally we don't focus on it.
It's only when someone gets injured outside of the series they race in where it becomes an issue.
Tony Stewart is just the latest example of a driver getting injured simply for doing what he enjoys. His third sprint car wreck in the last month got all the attention, and honestly it didn't even seem as bad as some of his others. His car didn't tumble end-over-end, it got ran into and the hit eventually was what did the damage to his leg.
It's always the wrecks we never think about that ultimately are the ones that do the damage. Even the wreck that took Dale Earnhardt away from us didn't look that bad.
His son years later in a Rolex Sports Car practice session had his own run-in with such an incident where he wrecked and his car caught fire. The burns were enough that he needed backup drivers for a few weeks so he could heal up.
It doesn't have to even be a racing incident that causes an injury. Look at Denny Hamlin when he tore ligaments in his leg playing basketball.
So why do drivers do what they do outside the track, knowing there's always a chance to get hurt? Simple answer is because they enjoy it. It's a release and an enjoyable experience for these drivers. No one wants to just be stuck in an office signing paperwork or just doing appearances for sponsors, which these days is very often. Drivers have their own ways of getting away, and there is always a risk of being injured.
Are they all going to stop because of that...of course not.
That's what they enjoy doing, that's what makes them happy. Sure some have bigger responsibilities, like having a wife, children, or running a business. But even with that, they are still going to do what they love. That's just how they are, it's part of their DNA.
Don't expect Stewart, Busch or anyone that enjoys racing at any level to stop. There's a risk, but that's why they do it. They love to do it.