I'm pretty anti-brexit, but I'm not sure whether I'm pro-rejoining. Taking the clusterfuck we've landed in and turning it in to somehow an even bigger clusterfuck may not necessarily yield good results and definitely won't be some silver bullet. The massive middle finger we'd justifiably get from the EU should probably give us pause.
What's done is done. From day 1 after the referendum it was obvious to everyone that the UK would spend the next 50 years trying to mitigate the impact of that ridiculous decision. Hotting the "rejoin" button is not necessarily a short cut to the end.