My perception of this, and this is my own take on things from memory but I admit it did influence my vote to a degree.
There was something that is now known as the Bloomberg Speech in 2013, if you are not aware of this Cameron made a big thing out of going to the EU to get concessions prior to the brexit vote.
Unfortunately Cameron did not realise that the EU would tell him to basically F Off. The EU if anything, applies everything to everyone with very few exceptions (if at all) and just because there was the threat of the UK leaving they were not playing ball
So when he returned with his tail between his legs it looked as if the UK had next to no power at all. There would have been more of a chance of remain winning if he hadn't promised what he couldn't deliver and didn't bother trying.
But as you say hindsight and all that...
Yeah, I think Cameron screwed you.
The UK was already outside the Euro and schengen and had plenty of special conditions in place to protect the city. So it wasn't the strongest negotiating position going in. But I do think Cameron didn't try hard enough as he wanted to scare the backbenchers as he knew they wouldn't accept anything short of total withdrawal.
Basically, I reckon the EU knew what position Cameron was in with his government so didn't want to even risk destabilizing the union by making guarantees that, if applied to all 27 members would essentially bring down the EU and that the Tories wouldn't accept anyway.
I do think Cameron could have reached a better compromise but we'll never know.
It also seems that Cameron was caught by surprise by the amount of third party interference in the leave campaign and had no good plan to combat it.
He basically unlocked the door and welcomed all sorts of nefarious people in!
And I don't think you're in much better shape now.
The fact that the best of your last three PM's is Theresa May is kinda shocking.