I get the sense that digital nomadism is akin to a multi-level marketing scam; the only people making actual money are the ones recruiting others to the "lifestyle" by advertising their blogs, books and guides (see OP).
Years ago I sort of did the digital nomad thing for about 8 years in Western Europe, but I managed to spend a good amount of time in every continent but Antarctica. I earned between $25k and $100k a year working about 10 to 20 hours a week and spent most of the money on alcohol and women. I had to work pretty hard the first couple years just to kick-start the whole thing though. The final year was a total blowout and…
"I spent a lot of money on booze, birds [women] and fast cars – the rest I just squandered" -- George Best