Of course, a good percentage of the AFD voters are actual Nazis and lost causes, but the thing is that an increasing number of people aren't voting at all because the existing political landscape doesn't have anything credible to offer. Due to the 5% cut-off for getting into parliament, voting for a small party is frequently seen as wasting a vote, which exacerbates the problem if none of the big parties are seen as deserving a vote. With fewer people voting, all it needs is every Nazi out there to go and vote AFD to create a scary high percentage of votes for them.