It could be 90% in favour of rejoining, but it wouldn't make much of a difference. The EU would need to see strong, long term cross-party support in Westminster before they'd consider it. The EU know that otherwise the issue is just going to keep re-emerging in UK politics so long as the Tories are ideologically opposed to the EU. I think the best chance the UK has is if the modern Tory party stopped being relevant electorally, because their membership's views aren't likely to change, and everyone in the EU institutions hates them for the damage their governments have done over the last 7 years.
I also would be really surprised if the EU would offer the same favourable terms the UK had before. Most likely they would need to show their willingness to integrate more in the union than they did before.
At least some percentage are just lying to themselves / the pollsters. We've seen enough bad-faith rejection of fact on this side of the pond to know that it's fairly common with shitheads who refuse to admit they're wrong.
It's the same why so many people support rich folk and in politics side with them
They either think they also will become mega rich or they think the rich people deserve their money (even though almost all the richest men have broken laws to make that money)
Having your own currency is not a special treatment at all - instead, the Eurozone is kind of an elitist club inside the EU that won't let everyone in.
The "British Rebate" (or whatever it was called) that guaranteed 66% of the British payments to be sent back to the UK on the other hand should be gone for good. Same for not being a member of the Schengen area or adhering to the rules concerning fiscal stability.