Bitcoin Exchange Questions

I was just wondering if the guys who sell bitcoins make a decent amount of money. I don't see many people in the united states doing it so I thought it may not be very lucrative. I was just curious if I was to buy 2 or 3k worth of bitcoins, and than piece them out if there was a decent amount of money to be made or no? Also is this illegal, or would I have any problems doing so. Thanks for any input, and help you can offer.