It's also possible to life off the art alone and skip all marketing. I think ordinary people tend to value classical (i.e. non-abstract) art more - it won't ever go into millions, but people are actually happy to pay a couple grand to hang beautiful/evoking/haunting masterpiece in their living room. Check out Beksinski's art for example [1]. He was your typical artist hermit type that hated self-promotion, and yet he lived off his art for 50 years. This route requires a boatload of talent and hard work though.

[1] (https://www.google.pl/search?q=beksinski+art&source=lnms&tbm...)