The answer is that it must be awfully hard to pull a bird with a microlight. Have you read a book called Propellerhead? It is the story of a City exec who decided to fly a Thruster to improve his sex life. He failed, which proves it can't work
Regarding anoraks, of course the anoraks don't mind being with other anoraks
But seriously, I don't think money is much to do with it. It is no doubt true that
those people that are presently attracted into UK GA often give up due to lack of money, but that's not the point. If a flying school was up front honest with everybody that walks through the door about
1. the very limited utility of a bare PPL for going anywhere
2. the cost of the options that will allow one to go somewhere
3. the inadequacy of the legal currency (12hr/2yr) requirement
4. the cost of maintaining real useful currency (say 30hrs/yr)
then a lot of people would walk out again, but those staying behind wouldn't be giving up due to lack of money. They might give up due to family/business/time commitments but people do that anyway.
At a suitable location, one could set up a really pro flight training business / flying club, with decent modern aircraft, and certain management practices that would encourage people to stay. I have not seen it done yet.