In the opinion of many, Donald Trump was able to win the election because of a carefully targeted social media campaign that focused on building a database of users and attacking those with ads and media, rather than focusing on pre-existing demographics.
By constantly vilifying Hillary Clinton, Trump managed to not only get people who liked and supported him to be mobilized to vote, but get a lot of voters who were on the fence to believe that anything would be better than voting for Hillary. To this day, I have family members who admit that they think Trump is an absolute moron and is unfit to be President, but that their hands were tied because Hillary was so evil they couldn't vote for her.
As President, Trump hasn't been able to do much aside from make headlines for erroneous, offensive, and borderline insane claims. When he does apologize for saying something wrong, he tends to sidestep the blame and place it on other sources, like the time he wrongly claimed an attack in Sweden was spearheaded by a Muslim immigrant. It wasn't. So he said he wasn't at fault because he saw it on Fox News.