I don't think anyone has got super-rich from canal vlogging but a small number have probably made a modest income for a few years and it's a bit enviable (if you don't mind talking on screen) to earn your living pottering about on the canals, making a video once a week, no boss, no ties etc. It's no wonder lots of other boaters have tried their luck at the same thing.
I follow a few hiking/backpacking channels from around the world and again, it must be pretty sweet to earn a decent income from doing the thing you love. Equally, only the best ones will be making much money from it.
I do notice the Foxes have a website selling merch and a patreon page with the top membership at £38.50 a month. I wonder how many top members they have? The patreon offers a private 20 minute video chat with the Foxes (the mind boggles what might be going on there, but I don't think they have an Only Fans page yet!). This personalised experience does seem to draw people in very closely, which I think is what Dora was getting at when she started this thread.