We don't really know you or the guy you're talking about, so there could be a million reasons why he behaved the way he did.
The only thing you can change is your attidude towards things like this. Which is really unhealthy by the way, just to put your view into a perspective:
You're creating a thread on a self-help forum "bitching" about a "beta-male" that didn't like you. So by those terms that would make you atleast a gamma-male because an alpha-male wouldn't give a fuck

(Oh and please stop using those alpha/beta terms, every human is way more complex than that)
So what you should take with you from this event are the following things:
Its totally ok not to be liked by everybody. Its like rejection by a girl, it saves you time.
There are always guys that will give you shit because of whatever reason. Personally, i just ignore them and if they cross a certain line i just call them out with something like "Hey dude, i'm just trying to enjoy myself here, so please stop that". But this happend maybe once or twice in my entire life.
And please don't judge people too fast, as i said, there could be a million ways why he behaved like that.
Just had somewhat of an epiphany last week when i watched the movie 50/50 (which i think is a pretty great movie btw.)
There is that one scene where the maincharacter (his father has strong alzheimers) talks to his psychatrist and bitches about his mom because she worries too much and he doesn't want to talk to her because she annoys him. The psychatrist then replies: " So she's got this husband that can't talk to her ... and this son that won't? ... makes you kind of a dick". And well that scene kinda hit me because my mom behaves the same way and worries about me all the time which annoyed me pretty hard.
But sometimes you're just so focused on yourself that you don't realize how selfish you're behaving.
So before you jump to conclusions too fast, just try to put your view into a perspective.