The EU may work for some, it doesn't for others, at present it is incapable of serious reform from within because that will upset the 'gravy-train', that's why its flawed, that's why ultimately it will fail. The US (even under Trump) has a better chance of restraining China, than the EU does in the future. Britain has a better chance of dealing with China on its own, in the future, than within a monolithic organisation. I would say the one hope for the EU is that Britain leaving will spur Germany and France to take charge of the EU cut through the bickering and drive it forward towards full integration, full steam ahead, consolidate the euro zone, those countries still outside it either join or sit on the back steps, no stops, no u turns, no more treaty's, just go for it! however if it doesn't do it soon, it will have no hope of catching China
I take your point about future generations, however that's inevitable, our grandfathers etc. did what they thought was right and there would be many saying something different at that time, somethings worked, others didn't, there will always be an element of the "the sins of the fathers being visited on the sons", we can only do what we think is right. Essentially most remainers saw Brexit in purely economic terms, most leavers in differing forms of political solutions.
One of the things that convinced me to vote leave was if you live in a large metropolitan area/city in Britain, there is a 'remainer' instinct, our large cities are becoming almost like the medieval castles of old, inside them you have a relative degree of prosperity, outside them you are almost in a wasteland. Wander down any high street in a small to medium size town and look at what has happened to it, shops closed, business gone under, or given in to the out of town malls. OK you will say that's progress, nothing to do with the EU, but if you live in one of these towns, it sure don't feel like it and the EU hasn't done much to alleviate the problems. Even when EU monies (which are our own to start with) come back in Project Form, most are 'window dressing' at best, forlorn attempts at covering the economic scars, giving temporary assistance at best, keeping people like me (for a time anyway) employed in managing the projects, but in truth, whilst achieving the objectives (otherwise you didn't get the money) but making little difference. The most important project that I felt really did have an impact was the first one I worked on in the North West of England, it was designed to help businesses get familiar with IT, web site development, training for company staff, even some PC hardware given 'free'. That did make a difference, because it was the right project at the right time, in the right place, it was not just chasing a 'pot' of EU money, which unfortunately that's what many projects become, they call it inward investment! apart from the that one project, I'd call inward waste.
I suppose we all relate to our own experiences, if your experience of the EU is positive then of course you want to remain within it, since you are already there, so to speak, then you need not worry about the rest of us... and I'm not accusing you of being selfish!