Not to plug a different platform, but on cruiser forums, there’s a whole forum dedicated to this. Hand in hand with how to make money on a boat is how much monthly expenses are. There’s a forum for that too- very detailed info on monthly expenses. Also a board on investing in order to cruise.
If you’re a techie, pmwedge basically laid it out. If you’re good with your hands, Janice laid it out. If you’re interested in that path, check out the book https://www.amazon.com/How-Make-Money-Boat-Businesses-ebook/dp/B0070O8QD2.
I’m landlocked first a bit longer, but have taken Automitive electrical at the local community college, gotten back into welding, will brush off my diesel repair/maintenance skills and am learning how to sew. A lot of people with boats are incredibly self sufficient. A lot of other people with boats need help doing anything.
Taking on passengers is a whole legal ball of wax. Suffice to say many people take family and friends for legs of trips and they “chip in” on the boat fund.
I’d give up any notion of a youtube/patreon channel as that market is saturated. MAYBE if you can come up with great content, but...