There are lots of youtube channels (and similar) promoting this idea. These channels can generate a lot of ad revenue for their creators. I'm assuming that's what they're referring to.
I would disagree with this, my small YouTube channel ( https://www.youtube.com/channel/UC6WpEeF48A7r032N486j1cQ ) generates a couple hundred a week at which point I rotate videos for newer fresh ones. And this channel is literally about saving money by buying things at thrift stores.