All of the numbers are not in yet but it is pretty clear now. Only approximately half of the voters voted for Trump. Considering that a lot of people didn’t vote at all, the result is that only approximately 25% of the U.S. adult population voted for Trump.
So who is at fault, or responsible for him winning? Trump won when people didn’t vote against him. All adults have a civic responsibility to educate themselves and then get out and vote responsibly if you want a representative government.