The guy you voted against might become your president (potentially this can happen to a little bit less than 50% of the people), so what

In the US, given the electoral system, this can be true for >50% or the voting population, and I believe that has happened. Hypothetically, with more than two strong candidates, well over 50% of the voting population could vote for a candidate who does not win. Given voter turnout rates, I believe many Presidents have been elected by significatly less than 50% of the eligible population -- a lot of people don't vote.

The US is messed up.