I think what you're describing is not "living paycheck to paycheck" which these days can be hard goal to meet for a lot of people.
I had thought of this recently. I have been looking for something creative I could turn into a business for several years. I'm a crafter at heart but I'm pretty "random crafty" Some things I only do once in a while, somethings I've only ever done a few times and then was done with it. I try out new things all the time but nothing really help up towards the criteria of me being able to do it well enough to have something worth selling, and/or having the passion and drive to put a lot of my time into it on a regular basis to maintain any sort of business.
So I guess at this point success will be actually having and maintaining a business. I've also thought, in the best case scenario, how successful do I want to be? Ever growing, if I were to be so fortunate, sounds exhausting. I'm not sure where I'd draw the line, but there would be a point that I would not want to expand any further, a point at which enough would be enough. I don't think I'm interested in having a brick and mortar shop.
My husband has his own business pursuits we're hoping will also be successful, but he's got a lot of school ahead of him for that first.
Edit: Suppose I didn't exactly touch on monetary success. I'm not very interested in that. We're pretty good at staying comfortably within our means, although this year was hard since my husband transitioned out of the military in December, but then again a lot of people don't find it to be a smooth transition.