You ignore that individual humans will change their political opinion as they age: Every year more and more remainers become leavers. This isn't the sort of thing where you can just wait for the leavers to die and then you win.

Someday, you too will be old. Guess how you will vote. :-) Some young person, much like yourself today, will be thinking that your death would make the voting turn out better and will be eagerly awaiting it. Eventually, they too will be old... and so it continues on forever.