The question is surely not if you personally or we collectively have benefited from being in the EU for the last 30 years, it's if you/we will continue to benefit from being in it in the future. Maybe you think you personally will, but many of us think that, however much we may have benefited in the past, we collectively won't benefit by remaining in, given what the EU has become and is becoming.
Although I agree that there is some uncertainty about exactly what might happen if we do leave, I suggest that at least some of the panic about Brits currently working in other EU countries being forcibly repatriated, or not being able to holiday in continental Europe as they do now are unfounded.
We, either as individuals or collectively, won't suddenly become less European simply by virtue of choosing to leave the EU, and suggestions that we will are little more than scare-mongering.