Because I can play it to a reasonable standard and it's good fun.
and
Because it can be played from a young age to an old age; as a team game or individually; against others or yourself or "the course"; and with a handicapping system that allows games of men vs women, young vs old, and adept vs novice.
Darts - a great team game at the pub, noone seems to care if you are rubbish, and I enjoy watching it on tv, too. Great for kids as it encourages quick, accurate adding up, deduction and multiplication.
Volleyball is my sport & my team is called Sons of Beaches
Each summer there is a beach tournament where I live and you see all these teams of fit 18 year olds who take one look at us and mistakenly think we are over the hill has-beens. Big mistake.
What's that saying about old age and treachery will always overcome youth and something?