True... the British were in the prefect position to play multiple sides against the middle... Brexit would have allow them amend things become the central hub and bridge for the US, EU, Russia and China... hell it could have become relevant again... they just had to not be so stuck up... but well... too late now... at least it would take a sh*t ton more work now...
Not by a long shot. The EU is to Britain what China is to HK. Britain was only as relevant as it was because it offered an English speaking gateway to the EU internal market, with local institutions able to effectively work as intermediaries to facilitate easy trade with languages, legal and other experts on EU trade; much like how HK offered similar for the the Chinese mainland market.
Brexit was about British 0.1%er vested interests getting their panties in a twist because of EU legislation designed to tackle their interests in sleazy offshore financial tax havens and money lauding centres. So they played the British nostalgia, nationalism and racism cards to get the uneducated, racist and delusional parts of the society to vote against their own self interest.
Basically, Brexit was a model for the HK riots, with the only major difference being that the British government itself has in on Brexit, while the HK government was firmly against that BS nonsense.
Had the British government not allowed a referendum, they probably would have seen HK style street riots.
But the end result is that with Brexit, the UK lost is biggest, and arguably only major competitive edge. What is the point in foreign companies setting up shop in the UK post Brexit, when they will not enjoy easy, tariff-free access to the EU single market? Especially when you have English speaking Ireland right next door offering what the UK just threw away?