Before I quit working, I sold my house and bought a boat. I have been around MANY who live full time at marinas, changing anchorages with seasons.....
It's possible to live much cheaper than most would think possible. I wintered over in Marathon, Fl at the city anchorage. You get a mooring ball, water, place to park a vehicle, garbage service, showers (shower on boat or shore) for a bit over $300/month. The motels peak season get to over $500/night......
I know several who were caught in Marathon last fall during the hurricane. I always arrived in Nov/Dec and left April/May to avoid hurricane season.....
There was a cross section of America, Canada and Europe down there. Some could barely afford $300/month, some might be called wealthy. But you meet many really fine people in a setting like that.
I highly recommend everyone who has a slight interest in boating to try that lifestyle for a few years (but most would NOT like to do it, many couldn't do it even if they tried). There is lots to see and learn that most miss. Just like the $800/month women in her car, you see things differently stepping out on a different trail.
This picture is of a "boat" where you could order breakfast over the radio and then run over and pick it up. You can see the sail boats tied up to mooring balls in the background.