Some franchises make great money, but many times it's like buying a $35K/year job. My next door neighbors bought a Quiznos, but hired a manager. Best I could tell they pretty much broke even. And that was a good location.
Many Quiznos franchisees sued the company.
If you can work round the clock and do it all yourself you might make a living. But if you have that kind of work ethic then you can get a job doing the same work and not risk your life savings.