Please don't mistake an honest assessment for pessimism. It's hard to look at any of how the last two years have panned out without seeing that many people have underestimated the problems both of leaving the EU in the first place, and of being out once that happens.
I've voiced before on AB (I think) that most of the problems could probably have been avoided if the referendum had been held *after* people had given a proper thought to what leaving would mean, rather than before. Instead we were offered a dishonest referendum, designed to kill the issue, and it backfired on, in particular, Cameron and Osborne's faces spectacularly. They ran away (or were sacked) before they could face up to the true fallout from their arrogance, but it still leaves behind a mess. I hope that May, Davis et al can sort things out, but they are running out of time and running out of ideas.
If, paradoxically, an increasingly dysfunctional plan for our future outside the EU encourages more people to support leaving, then so be it. The EU's intransigence may be unhelpful, but it's no more unreasonable than Jacob Rees-Mogg's bizarre and totally false insistence that "we hold all the cards" (unless he meant a Yarbrough, I suppose...), and rather better-supported by reality.
As it is, there's little evidence that, overall, public opinion has changed. Perhaps more people are flocking to leave, concerned by the EU's inflexibility, but, equally, "Regrexit" is pushing some back the other way. But mainly, if you hated the EU to start with you'll probably hate it even more now, and if you hated Leave to start with then the inability to come up with a coherent plan is going to convince you that you were right to have voted to stay in. We see what we want to see.