IMHO,a big part of the reason people give up is that the current UK PPL training scene doesn't seem to believe that pilots should have fun, actually discourages them from the kind of flying which creates that fun and seems determined to engender such a fear of messing up that its no wonder people stop flying.
So we get pilots who have to create a plog for every trip. Who are scared of leaving the local area, plog or no plog. For whom diversions from the planned course are a big deal. Whose idea of a long trip is 2 hours. For whom a foriegn trip needs at least 6 months planning. Who think that its a big deal to call ATC because they might mess up the call. Who think its a big deal to get a zone transit. Or to fly low. Or to beat up a runway. Or a beach. For whom a steep turn is 35 degrees. And for whom being closer than a mile or so to another aircraft is dangerous. Who get the whiz wheel out to give an estimate of time to a point. Who still use a whiz wheel for goodness sake. Who divert in marginal but flyable conditions.
Please don't misunderstand. I do not advocate breaking height or visibility rules (much) or beating up noise sensitive villages. And I don't blame the pilots concerned; we all work within our experience levels. I do blame the system that produces them and fails to show them that there's more to flying than 2400ft straight and level. I just can't be surprised when pilots get bored of that within 2 years.