Well, an argument can be made that his party did give up Istanbul and Ankara in the previous round of local elections (albeit with quite a fight), so it serves to reason that they're not entirely opposed to the democratic process (most of their money is hidden in off-shore tax havens and not Turkey, so they can always bail if the political scene turns hostile towards them).
The issue is that, no matter how you see the current political climate, the dude won the recent elections fair and square (as far as we know).
The people voted for this, so let them enjoy it. To me it's like Brexit, except I'm living here and watching it happen to me as well.
It's not a fair country, lol. But, regardless, things do work a bit differently here as people are aware of the fact he owns and controls the main news channels - folk aren't under the illusion that they're fair and balanced, so that metric isn't as relevant as - say - an election in the West where people are more likely to trust their media.
People went with him mostly because he promised stability, and the opposition don't have a great track record with that (even though they really gave it their best this time around). A lot can also be said about Kılıçdaroğlu and his refusal to step down... But that's a much longer discussion.