I started with the original Handi-Quilter frame (yuk) and an old Pfaff and I outgrew it in about two months. I upgraded to a Juki and a stronger frame and then a couple of years later I bit the bullet and bought a Nolting with a 24 inch throat and a 12 foot table. In retrospect, I wish I'd have done this first. But it was such an investment, I wasn't sure I could justify it. But I've had it for five years and it is a great setup. I started doing customer quilts about a year after I got it.
I took classes on doing pantographs and stencils and on how to use rulers and then ultimately taught those classes for the dealer that I bought the machine from.
I don't rent my machine to other quilters because of the liability and because I usually have a quilt that I need to get done loaded on the machine. I also don't want the hassel of renting it.
Could I support myself with quilting? Nope. I do make money quilting for others, but I couldn't meet my bills and feed myself if the only money coming in was through quilting. It can be a very fluctuating market. It depends on the season and the economy. When your're busy you are really, really busy and when your're not you can be really, really not busy.
I hope this answers your questions