Replace "should" with "could" and you'd be right. Each vote would be genuine if its conudcted according to law.
Kids learn at an early age that when you lose, you lose. They usually grow out of "best of 3" or "best of 5" before age 10.
Even a 5 year old knows that "best of 2" doesn't work.
Most democracies have regular periods where you vote. Are you suggesting that since there will be a new US Presidential election in 2020 that Trump is now no longer legitimate? How would that circumstance be any different that a referdendum?
Voting isn't wrong.
What is the implication of you trying to tie the institution of democracy to childhood antics? Are you suggesting that a vote is no different that chance? That the opinion's of people that change are no longer legitimate?