Whether the candidates themselves, all of them, can be trusted is a much more serious problem with democracy, I think, than "dumb" people affecting the vote.
dumb people vote for dumb things, whether issues or candidates.
Also, gay marriage isn't really a complex issue: Even the dumbest person understood the consequences of banning it, they just were that sadistic. Agreed on Brexit though.
As for the implications of your premise: Do you feel comfortable in not having a say whether you are taxed more, have your hobbies criminalized, or get sent off to die in some awful war somewhere so that some jerk can get rich? Because that's what you ask for when you say some obnoxious technocrat is fine running the country with no input.
And before you mention passing an exam or something to vote, that's just a direct path to corruption and disenfranchisement.