Lots of these kinds of people nowadays have income streams through blogging and podcasting, advertising on their blogs/podcasts, or through writing a book that they then sell.
Internet advances mean many can offer consultancy services - either regular consultancy (accounts, law, economic advice etc) or specific to their adventure (maintenance, guidance for others considering trying it out, etc) even on the go - on land or on water.
I have heard quite a few different blogs and podcasts from people like this, where they take the family out for a couple of years adventuring or even change lifestyle completely - and there are various ways they have financed it, including saving up beforehand, having their house rented out, or income from blogging/advise etc .
"Family Adventure Podcast" is one where there can be some interesting stories to consider, if you are interested in taking some time out with your family and how it can be done.