A clear majority of the British public now believes Brexit has been bad for the UK economy, has driven up prices in shops, and has hampered government attempts to control immigration, according to a landmark poll by Opinium to mark the third anniversary of the UK fully leaving the EU single market and customs unions.
The survey of more than 2,000 UK voters also finds strikingly low numbers of people who believe that Brexit has been of benefit to them or the country.
I don't see how any of that implies failure. The goal of Brexit was for the UK to not be part of the EU. The UK is not part of the EU. Seems like success to me.