Ok, as you've asked directly I'll give you my honest opinion for once rather than my usual pot stirring
Mainly I think it's the expectation that they will receive a better funded public sector (which is a huge part of the electorate) but not understanding that there is one pot of money and the services it can provide depend on the size of the pot, without realising the only way that pot grows is if they pay into it.
Secondly. there is also a huge myth that despite no Govt ever saying that they want to abolish the NHS, many have been brainwashed into believing it. There is a certain elitism to a lot of the MP's that doesn't help them either despite whether they are any good or not, lots of the GP simply can't get past the fact they can't relate to people like Rees-Mogg for example. I actually like him, but I can understand why he hasn't gone for leader as there is no way he could win a GE. Finally I think a bit of jealousy and envy of the 'haves' and 'have nots'.
If I was being mischievous, I'd also guess that the average IQ of a Conservative voter versus other parties (not on here before anyone gets into a dick waving contest) is a few points higher.