Admittedly, I don’t know much about Brexit, but from what I have been exposed to, it seems like a decisively economical and political impairment that made travel and business with the rest of Europe more difficult and costly. Since it is so highly criticized as a terrible move, why doesn’t the UK just rejoin the EU?
Many good answers in this thread (and some stupid ones) but there are a few critical issues that the current British government will not accept.
First, currency. GB does not want to give up control over the pound, and their previous agreement did not force them to adopt the Euro. There are several other EU countries that have not yet adopted the Euro, but all except Denmark are obligated to switch over once certain criteria are met. GB might be able to negotiate that privilege again, but the EU is in a stronger bargaining position now.
Second, immigration. For as much as their country is suffering from their own strict immigration policies, the conservative government is still making political hay out of xenophobia and bigotry. Reopening the borders would be a tacit admission that their rhetoric was bullshit.
Third, taxes. Joining the EU means contributing to the EU, and while their nation may save money overall due to improved trade relations, the conservative government has made the cost of admission another talking point.
Basically, the current government would have to renegotiate readmittance to the EU, and they would get a worse deal than they had before. Doing so would make it obvious that leaving was a mistake, and their government could only be consisered an objective failure. So they won’t do it, even if it is the best option available.