Monocock/acw
Definitely this isn't the problem. There is huge wealth in Sussex, more than just about anywhere except London. Just over the airfield is a private estate with few houses below £1M. But almost nobody with more than 2p is being attracted into Shoreham.
No, it would be easy to draw in the "BMW Z4 owner" crowd which is presently piling into £600/year gyms just for a diversion. It would take a polished operation to do it, and that's never been done, especially not at Shoreham where there are and always have been far too many schools for anyone to do more than just hang in there.
And they all offer the same product. The nearest anybody got to doing anything other than the standard decrepit 1960s/70s metal was ACE, who got two brand new planes, but what did they get......... Cessnas!! A complete waste of £140k a piece, because this just buys you the same WW2 machine whcih doesn't attract a different sort of customer.
THAT is the real problem - the airport's policy of permitting too many schools to set up. At any normal GA location, one needs just three schools: fixed wing, aeros, rotary. Plus perhaps a strictly commercial one operating twins. Anything more is just going to make sure everybody gets driven into the ground.
The other factors, e.g. the types of individuals and their behaviour which are more directly responsible for some of the higher profile failures, is only the straw which breaks the camels' back.