"I don't want the nazis to come into power, but I also don't want brownshirts to assault me and my family, and I'm pretty sure I'll be OK if I keep my head down" is an understandable sentiment, if a bit cowardly.
Hitler gained power because non-Nazi conservatives such as Hindenburg and Papen[0] installed him in power, because they thought they could control him, and because they viewed him as a lesser evil than the socialists and communists who were also jockeying for Chancellorship, and because they saw appointing Hitler as Chancellor as an end to the gridlock in the Reichstag – the result of the election was that Nazis were the largest party but did not hold a majority, but the next two biggest parties, the socialist SPD and the communist KPD, could not unite against them because the KPD was under instruction from Moscow not to cooperate with the SPD. Leading representatives of industry and finance also pressured Hindenburg to install Hitler, because they saw it as an end to the political chaos and also as a defence against the threat of the socialists and communists, who might harm those economic interests if they gained the Chancellorship.
Although Hitler only had 37% of the popular vote, he also had substantial support from Germany's elites. He gained power because he convinced the people with the power to give it to him. Of course, after the war, many of those same elites tried to pretend that their decision to give Hitler power never happened, or that Hitler had somehow forced them into it.
[0] Papen was not a Nazi at the time Hitler came to power. He naïvely thought he could control Hitler and the Nazis; after a while he learned that not only could he not control them, they could control him, but by then it was too late. And then he became a Nazi himself.
Also agree with the point about elite support. Not every supporter counts equally in terms of political support. Even in democracies this is the case.
Not in this case, Weimar Germany used proportional representation.
I personally think that proportional representation is superior to first-past-the-post, but actually you could argue that PR played a role in Hitler coming to power. PR systems encourage multiparty systems as opposed to two-party systems. Multiparty systems can sometimes produce great political instability when nobody has enough seats in the legislature to form the government, and then there can be weeks or months of backroom dealing to try to form a coalition government. It is a scenario which commonly occurs in a number of countries with proportional representation (such as Belgium, Italy, Israel), and it was in that same scenario in which Hitler convinced the President to appoint him to power.
(Germany now and then is a parliamentary republic, the President is a non-political figurehead, the Chancellor is formally chosen by the President but the President is supposed to choose the leader of the largest party or coalition in parliament.)
You could argue that the specific form of proportional representation being used – the list system – was a factor. Countries which use the list system (such as Belgium, Italy and Israel) tend to be more likely to have unstable multiparty systems than countries using milder forms of proportional representation such as instant run-off or single-transferrable vote.
After WW2, West Germany moved away from the pure list system to the current hybrid system in which voters vote both for an individual candidate and a list. That change was inspired by the lessons of the early 1930s.
The shape of the electoral system was possibly a contributing factor to the Nazi's rise to power, but it was only one factor among many. Many other countries had (and still have) the same system and yet they didn't end up with someone like Hitler in charge.