I guess the key question is, "What is making a living?"
I spent most of my 20s and 30s going from job to job surviving and making some extra cash on ebay. I tried multiple times to "make a living on ebay" but couldn't do it. I know have a well paying full time job and play with ebay on the side. If I could make $25K full time on ebay, I couldn't survive on it. I could never make what I make now on ebay and would never consider it until I get old and retire.
Considering I put in 10-20 hours a week in fun on ebay and only make a small amount, I can't imagine the work necessary to make $50K or more if it's even possible without miracle products falling from the sky. And keep in mind, I don't mean $50K or more in sales, I mean in take home profit that can go to bills, vacations and life.