I can’t imagine something like that being as cheap as you describe, even if it’s not a multi million dollar vessel.

To add to some of the excellent answers: There is a whole category of folks who do van life, but it's sailboat life. They live on the boat full time and go extremely low-budget -- few of them are wealthy at all. People get hung up on "yacht" and all the baggage that word brings. Many purchased a boat in lieu of a van or a house. So even if you spent $100k it's a cheaper life than on land in most cases.

Examples of low budget sailors you can check out:

Sam Holmes - I don't know what he paid for his current boat but he's super frugal. I'd be shocked if he paid more than $15k and it was probably a LOT less, knowing him. While back in the US he was sailing a boat (Bayfield 29) he got for free.

Sailing Uma - While this couple are now doing much better financially (thanks to their Youtube content) they originally paid $3k for their boat, put as I recall about another $3-5k into it and have been sailing ever since, including across the Atlantic and up to Svalbard, Norway, Iceland, etc.

Wind Hippie Sailing - Holly, who is pretty damned poor, sails a Grinde 27 which was a real fixer upper when she bought it. Not sure of the price but probably under $20k.

There are of course a ton of sailers out there who are not visible. I know of a couple of people who got their boat for free and have sailed at least from the US West coast to Hawaii or around the Carribean living on practically nothing.