We can't all be net receivers from the budget, more has to go in than comes out.
We benefit by being part of the free trade area that gives us over 40% of our exports.
You seem to be arguing that by leaving the EU we will be better off by the value of our payments and ignore the fact that our payment is based on VAT which is based on sales of goods and services. The UK economy was worth around $2.6 Trillion USD in 2016 (the most recent figures I could find with a quick google search) which corresponds to a Tax Revenue of approximately $1Trillion USD over the same period.
Growth was forecast at 2.2% in 2016, it is now expected to be 1.5% this year, dropping to 1.3% by 2020 and only rising to 1.5% again in 2021. I wonder what could have caused those drops in growth forecast?
If we experience drops in growth of this much on the tax revenue that equates to $9Billion USD per year, so even if we accept your little englander argument that we get no benefit whatsoever from investing in EU infrastructure we stand to lose almost as much just on the tax revenues as you expect to save. If you add in the losses from having to pay tariffs on our trade with the EU and other markets then the net losses are far greater than any wishful thinkng on the side of a bus.
Even on a simple economic argument your basis for leaving the EU is laughable, if you add in the loss of influence and support we will experience by leaving a trade bloc comprising 20% of the world economy it becomes downright tragic.
Aha I hear you say, China is growing exponentially, India is a massive economy and what about all that Scotch the Japanese want to buy? Donald Trump loves us and will give us a deal whereby we can sell them all the Unicorns they can take and our NHS will be safe from Kaiser Permanente taking it over.
China and India are both growing on the back of cheap labour producing items we want for next to no money, they are not going to start buying our manufactured goods, we will lose our pivotal role in the world ecoomy so they wont need our financial services either. The USA have stated they will be looking for deals that benefit them first and foremost and will be addressing trade imbalances, we will get a fax with their Ts & Cs and a take it or leave it note from the Donald. It will almost definitely include access to our healthcare market and accepting their food which doesn't meet current EU regulations.
We won't have a hard border with Ireland becaue if we do the IRA will go back to their old shenanigans but we can't have soft border because we have taken back control. Rotterdam is recruting additional customs and freight agents and is expanding it's freight facility. Dover has done nothing and is now to late to have things in place by 2019.
Explain again how well it's all going.