You can do a lot of flying on a gross income of 25k, if you live a relatively simple life, don't go out much, don't have anyone to support, live in a cheap flat or with your parents, etc.
However, the UK is not as bad jealousy-wise as some other places. I know a pilot in Germany who bought a very nice IFR tourer which came M-reg. It was on M-reg only because the previous owner actually lived there. If you don't live there, you have to be a turboprop or bigger to be able to go onto M-reg.
So M-reg on a ~ 1500kg plane is a priceless registration, as both maintenance and pilot licensing are based on FAA papers, it avoids the need for a trust, avoids any occasional anti-American prejudice around airports (or in certain obvious countries), etc. And the IOM is in the European VAT system so you get a cert of free circ.
But this German pilot immediately transferred it to D-reg. Cost him thousands, obviously, and loads of hassle. When I asked him why, he said that in Germany people think you are fiddling your tax if you have a foreign reg plane.
I doubt any other country in the world has such a high level of population compliance - except possibly Japan.