By the numbers
I had occasion recently to receive some advertising information from a major astronomy magazine which contained the results of their reader survey. As you would imagine, amateur astronomers are overwhelmingly male, upper-income professionals, but I was surprised by the fact that more people reported having attended a star party (19%) than belong to an astronomy club or observing group (15%).
Mean age: 52.6 years
Household income: $95,800
College grad or better: 68.7%
Professional/managerial/technical career: 69.1%
Involved in astronomy hobby (mean): 21.3 years
Replacement cost of current astronomy equipment (mean): $2,614
Average hours per month spent on astronomy activities: 8.9 hours
Readers who describe themselves as intermediate/advanced: 61%
Average magazine subscription: 6.3 years
Actually, this correlates pretty well to the demographic makeup of my club—or at least he folks who ever show up for anything (about 10% of membership). So I reckon this is probably a pretty good description of the people who are really involved in the hobby. I'm sure lots of kids are interested in astronomy, at least in general, but it's really more of a hobby for grownups since it involved staying out late, owning plenty of equipment, and possessing more a little patience.