Just compare the economic growth per capita of Norway (not in EU) with Sweden (in EU). It's at best an exaggeration that leaving the EU is going to have a significant deleterious impact on the UK.
Investment into renewables, as one example among others. Not that such investment shouldn't take place, but it has nothing to do with free trade, and I would much prefer a large carbon tax with minimal bureaucratic overhead than the centralized EU as-is allocating capital to ventures that the bureaucrats have decided are worthwhile. It's the globalist, big government and centrally planned solution to climate change.
Also two percent is a stupefyingly large amount if it were simply about effectively administering a FTA (and it isn't as per the above). NAFTA on the other hand requires roughly 0 percent, which is markedly better. Given the precedent of low overhead FTAs, I don't accept the premise of the EU.
Wouldn't it be better to replace the EU with an expansive multilateral free trade treaty that encompasses the same states? Why do we need an additional layer of government?
The chains are still on because the UK still needs to trade with said bureaucracy, and of course the fault of that lies with the EU's bureaucratic nature itself instead of the UK's decision to exit.
Ultimately we should want the EU to be eliminated entirely and replaced with a multilateral free trade treaty, and UK's exit is a very productive step in that direction.