our band's not even "professional" and the experience already has a profound effect on my life.
band's been in existence for just one and a half years now. since we have day jobs, we gig about once or twice a month, spend time (and money - ack!) recording weekends.
what do you expect to get in return for investing your time and other resources for the band? what level of committment are you willing to give for your band? in our case, i think it's a good thing that we're not at all taking everything too seriously. not out for fame, or the money. just a chance to express ourselves.
i also had a similar dillemma when i first joined this band. i was concerned that if i started jamming, and then gigging, i wouldn't be able to stop myself from devoting my fullest attention to the band, to the point of making work (and other responsibilities, such as family) a mere second priority.
being in my band gives me an outlet, a break from the monotony of work. because we're not a "professional" band, there's no pressure. playing pays for itself - it doesn't matter if we spend on our rigs and spend on rehearsal/studio time and recording time and at the end of the day, play gigs for free, long as we get to play. my point is, you find something that you want to do in life, the opportunity presents itself, (with a chance of getting compensated financially) then you should pounce on it. you'll never regret it. otherwise you'll be old and gray and thinking about that day when you decided not to join a band and what could've been had you acted another way. if you do join and it doesn't work out for you, heck at least you gave it a shot.
my two cents.