I've been reading about business history for decades, I enjoy it. I can't think of an example that matches that setup. Ideas like the pet rock or chia pet or electronic dancing flower pots jump to mind, however my thinking is immediately that: well, they weren't such terrible ideas then, lots of people wanted to buy those things.
A combination of disposable income and endless desire to be amused/entertained, is a potent consumption formula. The pet rock for example was a relatively inexpensive tchotchke of very temporary curiosity and amusement. People love to be amused, entertained and to have trinkets to talk about or show off. A lot of seemingly bad ideas fall into that space.
Many, many companies make bank, by taking classic ideas, and executing them well.
It's like Joe Cocker made many obscure songs into mega-hits.
Until done properly, or combined with other ideas or good marketing.
Until they make money, they are derided as "terrible ideas."
However, HOWEVER, there are/were some gigantic risks Airbnb was taking, I will agree with you on that -- the risk of people staying at random strangers' houses and the wide spectrum of horrifying experiences that can lead to. There's an excellent Bloomberg article that does a deep dive into Airbnb's somewhat-shady "Trust and Safety team"[1][2].
The point I'm trying to make is that although the idea came with certain inherent risks, skillful execution can mitigate those risks significantly. Similar risks were also attached to Uber's idea of random strangers offering rides to people, and those risks were somewhat mitigated as well.
[1] archive.md link: https://archive.md/nyBFY
[2] original article link: https://www.bloomberg.com/news/features/2021-06-15/airbnb-sp...