There is a man that never says hi to me, what to do?

I understand that in major cities, especially in Southern California, people aren’t as nice to each other as apposed to rural areas and small towns where everyone knows each other.

Blame it on the fast paced lifestyle, technology, the need for instant gratification with no patience to deal with anyone, sitting in traffic, physical proximity, lack of personal space, whatever you want.

I say hi to all the neighbors even though I don’t know any of them, and most of them say hello. But there is this one dude, who does not even acknowledge the fact that I greeted him.
I used to think, maybe he’s having a bad day, or that I didn’t say it loud enough, or that he is deaf or doesn’t speak English. But I’m not gonna make up excuses for him anymore. How can people suck so much?

I really don’t want to ignore him, because I “must” know why he sucks at life so much. I’ve thought about just yelling things like “So you really didn’t hear me huh?” or something similar, but that’s not gonna solve anything.