eeeThe UK was paying the EU ~140 million GBP a week. The .15 $/GBP means that as long as the UK economy was worth more than ~1bn GBP a week staying the EU was a better option for the GDP
Yes, but it's not like that money is sent directly into the void. The UK (to my understanding) got about half of what they sent directly back in the form of a rebate. A billion pounds also goes toward international aid, which will end up being paid regardless of EU membership. On top of that, they save shitloads on trade. Because of their membership with the EU, many American companies traded through the UK to the EU. In addition, various private citizens also get paid in subsidies from the EU (~£4.5 billion last year), and various private organizations received about £1.5 billion in total. Add in the harder-to-calculate-cost things in like peace in Europe, having strong allies with Germany/others, and the potential to lose Scotland and Northern Ireland, and you could easily pull together a strong case directly contradicting what you say.
On top of that, a good portion of the money spent by the EU indirectly benefits the UK in a very hard-to-measure way.
There are still fees that go into the EU, and the EU is a bureaucratic nightmare. I'm not pretending to know what I'm talking about on all the issues, but your specific argument isn't necessarily correct.
And to answer the OP question, that largely depends on how the UK handles itself. I'd say buy in a bit tomorrow and see how you do.