There are enough different types of small business opportunities out there so that everyone can find something that will work for him as long as he does some research to find the right business for him. Also, a person needs to have realistic expectations.
I had a friend who quit a high-paying job to start his own business. Several years later he was broke and working a low paying job. Not everyone is going to make a fortune operating his own business, so don't give up your day job until you know you are going to make it.