Really? I may have just found myself a new hobby. Search for incredibly unique (and worthless to me) domains to see if I can get people to squat on them. Heck, it could be a game ... I could get all my friends to make bingo boards ... or maybe see if I can think of some scrabble like rules.
They buy domain X and then they put generic advertising, maybe keyword based, on a cheap bulk hosted site. They measure for a few days - is this bringing in lots of revenue? If not, they cancel the purchase, using a "grace period" available to users of the registry in case of mistakes - the purchase is unwound and they are refunded the fees. Domain X is now available again.
In principle this is forbidden for major TLDs but it's still possible and unscrupulous vendors help them do it, albeit it may now attract a fee if you do it enough that the TLD registry detects you tasting.
I am sure, in the past, one of the domain registrars took the liberty of actually registering your searched domain, deliberately, so that you had to go through them to get the domain later on? - I can't remember who it was, but it was an automated process.
I know it was very shortly stopped once people complained, but it goes to show that it has been done before.
Getting rich off domain's - sounds like a solid business plan!
I've got no evidence except anecdptes, but I've heard claims that GoDaddy used to do this a lot. For this reason I've only searched a domain I was going to immediately buy, otherwise I'll do a whois lookup to see if it's registered.
Within this, was the comment that reminded me which company it was I was talking about (https://news.ycombinator.com/item?id=2327152) - Network Solutions used to do this - and there is a Wiki link in there which gives the process a name! TIL! :)
I remember something about registrars doing this so the domain you wanted wouldn't get snatched by someone else while you were in the process of buying it. Made more sense back in the time when far more basic names were available and such collisions were probably common for high-value domain names. Now it's two people finding the same needle in a haystack.