About a year ago I built a number of micro niche sites aimed specifically at generating adwords income for high ppc terms. They weren't especially pretty but they were a good exercise and more than paid for themselves.
At the point I sold them (22 sites) they were generating about $190 a month in adsense revenue, all this from me buying 'keyword in domain' urls, having a relatively good eye for writing seo copy and building some inbound links.
I sold the lot on flippa for just over $1k, so I suppose it made me about ~$300/mo for a year. I know of some individuals who have over 1,000 domains running (across some of the most random niches you would just laugh at!) so I think it's a pretty decent passive business for them.
I built (literally) a couple of these a few years ago while learning about SEO and never did anything else with them. At their best, they were making something like $300 per month (combined). With the last Google algo update the rankings are pretty much screwed and these sites now make something like $20/mo.
I also know some people with hundreds or thousands of these kind of sites and I can assure you they're not happy.
Building a business that depends on Google's algo to be profitable doesn't make any sense to me.
EDIT: When I say it doesn't make sense to me I'm talking about side-projects where the goal is passive income. If you're going at it full-swing and plan on pivoting as required then it can absolutely be a genuine business model.
I am acutely aware of how well some people can do but I just didn't have the time to do more back linking / articles, so for me I was more than happy with the return.
At the point I sold them (22 sites) they were generating about $190 a month in adsense revenue, all this from me buying 'keyword in domain' urls, having a relatively good eye for writing seo copy and building some inbound links.
I sold the lot on flippa for just over $1k, so I suppose it made me about ~$300/mo for a year. I know of some individuals who have over 1,000 domains running (across some of the most random niches you would just laugh at!) so I think it's a pretty decent passive business for them.