I've been on ETSY since 2011, have over 450 sales and total gross revenue over $28,500... not setting the world on fire, average is just over $3200 per year. I had my own website for a few years and at first it paid for itself, then sales dropped off and the cost was more than I wanted to carry... the $.20 per listing for 4 months equaled about 70 listings for what I was paying per month for my own site... it was a better deal for me. And as was said above, it's not to make a living, just to pay for the costs of being able to do more wood turnings... I stopped doing pen about 6 or 7 years back and concentrate on mostly pepper mills and bowls, with a few other turnings thrown in for fun... there has been some changes in their fees and structure over the years and fees have definitely gone up of late, but still a better deal for me than working my own website.
It's a good way to get established on the web and to see if you want to do your own website at a later date...