A lot of them sell for much less than (monthly revenue) * 12. I haven't personally purchased a site from there, but I know people who have.

You don't need to buy something from there -- you can simply use the site to find niches where people actually make money.

Making money online can be done. Example: I started a Minecraft server early on, sold in-game benefits, and now make $5-15K (depending on season) per month. A friend of mine makes way more. Here are the stats he sent me recently: https://i.gyazo.com/81718cef2295bbf4df8a6d9892d140c1.png

One of DHH's bits of advice is to find a niche and focus on profiting enough to support yourself. The internet is the best place to do that.