Even then I don't really get it - he's clearly not tied to a specific location.

I'd be willing to bet that even a regular home (unit/flat/apartment/small house/whatever) can likely be rented for 1/5th of London rental rates, if you look in the right places: i.e., not in major cities.

Cities are expensive; Being able to work from "anywhere" makes it quite easy to make your money go a lot further, particularly in terms of housing, without resorting to being a glorified homeless drifter.