Rejoining the EU would mean giving up the pound and adopting the euro. The British are not ready for such a big step.
They weren't willing to give it up before, so that probably tracks.
As an European I don't want UK to join back the EU. The damage is already done and cannot be fixed.
As also a non-UK European, I don't care. Stay in or stay out. Stop bitching about what needs to be fixed. I'm not wholly heartless, so I would be OK with the UK rejoining if they wanted to.
As a Brit, or should I say English since it seems at least Scotland doesn't wanna be part of UK anymore if given a choice, it seems to me that talking about rejoining the EU, as though the EU countries will just say "welcome back" after the UK has basically "acted like a d*ck" for most of the time inside the EU, shows precisely the kind of arrogance and feeling of superiority that caused the Brexit mess in the first place. Maybe in 25 yrs time perhaps our country / collection of countries/ whatever the UK looks like by then, might be humbled enough to be seen as a helpful partner within the EU....