Odds of Getting In
Judging by the thousands of items being sold online, according to Craftcount, there are decent odds at making real money at this...if, and only if, you're willing to put in the work and time. And believe us when we say that being an Etsy seller is work. What is now a fun hobby will soon become your nine-to-five grind (source).
The good news is that that's really the only thing you need to do to get into this job. There are plenty of art and craft sites out there—just Google "sites like Etsy" and you'll be given whole long lists of alternatives. Branching out into other sites will double, triple, quadruple, etc. your list of potential customers, but it will also double, triple, quadruple, etc. your potential workload. If you've got successful shops on five different sites, you're going to be one busy bee.
But if you're willing to put that kind of work in, then Etsy is your handmade, upcycled, vintage oyster.