It is not as if there are no costs to British citizens if Britain remains in the European Union. Just because Germany wishes to underwrite Greece, Spain, Italy, Portugal and, in time, France, why should the average Brit want to do so?
Britain has enough sovereign debt without taking on the burdens of southern Europe, which is exactly what Germany's plan is for the EU. The Brits can't afford it. Neither can the Germans, by the way. In fact, no country can afford to bankroll these countries. The Angela Merkel plan makes no sense.
Greece, Spain, ltaly, and Portugal should, and will in time, go bankrupt. They could then do a restructuring with their creditors and begin anew. Why should their neighbors be on the hook for their profligacy (and the stupidity of their lenders)?
Besides taking on the debt of others, the average Brit should be concerned about the regulatory regime installed in Brussels. Gradually, the absurd labor and regulatory rules of other European countries are being implanted on EU members. This just means weakened economies. Of what benefit is a weaker British economy to the average Brit?
What does Britain give up if it leaves the EU? I guess it loses the goodwill of President Obama, who has never found economic freedom to his liking. British trade will suffer only if Britain itself erects large tariff walls. If Britain can resist that temptation, they will do just fine. Better, in fact, than the moribund European Union, which has had no economic growth for over a decade.
Politicians and media pundits have a different agenda. They don't care about the take home pay of the average Brit. So, they fear a Brexit. But, the average Brit would benefit from Brexit with higher incomes, more economic freedom, and more control of their own destiny.