Yes, there are numerous ways of making money from Flash-based games, including (but not limited to) advertising, sponsorships, micro-transactions, or simply selling downloadable copies of the games.
As I told you in response to your almost identical question on GDNet however, most games only make a small amount of money or even none at all whilst the most popular and successful titles can make a good income. Do games development (and try to earn money from it if you like) if it interests you, not to try to get rich. Game development is hard, and if you're most interested in making money you're probably better off with a steady job instead.
Why do I have the vague feeling you might just be spamming though...? :huh:
Hope that's helpful to someone, even if not to you.