Re: Dealing with not responding to "hi"?
I'm in college too bro and I just think it's on them.
You can't always possibly walk up to them and make a conversation. You might be busy, running to a class, etc. So sometimes you just say hi, wave, smile or wink.
Unfortunately, school environment is full of socially incompetent (so to speak) people who might be introverts who wanna avoid the smallest kind of social interaction, or egoists who think they deserve some higher level of acknowledgement or in rare cases, both.
As you said you shouldn't be upset about this. If being social makes you happy, you always smile, always say hi, don't let anyone affect that otherwise.
About calling them out, if she's hot, why not?
It's not about who I was or who I'm going to become.
It's about who I am. Do it right here, right now.