Sports can simply be recreation or an occupation. And sometimes, like in the case of professional baseball, it can be recreation pretending to be an occupation. We're not picking on baseball, it's not like we did something mean like comparing it to golf or anything boring like that. Wait a minute. But enough of that.
Extreme sports have no beginning and no end.
It is an evolution of what has existed in some form or another and what is yet to exist. This being the case, there must be as many boundaries to be created as now exist to be broken. Heavy man, but if contemplation is not your thing you should fret not. No need to seek out the Dalai Lama or subscribe to New Age weekly. There is no pro or amateur, only the evolving and the exulted.