Let's start with a little defining of introverts versus extroverts to avoid any misunderstandings.
Google explains that introverts tend to recharge by spending time alone. They lose energy from being around people for long periods of time, particularly large crowds.
Extroverts, on the other hand, gain energy from other people.
This means that we introverts get exhausted. Exhausted just by going to work, going to class, walking to class, or even eating dinner if it means we're around large crowds. Don't criticize us for it.
If you're an extrovert and you see someone sitting alone, ask yourself, "Are they lonely and need someone to talk to? Or do they need a break from human interaction for a little bit?"
For extroverts, yes, it's human nature to want to go sit with someone and strike up a conversation because you just like being around people. But introverts can't do that all the time. So, if in that same situation, you think, "They're weird for sitting alone or wanting to be by themselves," then take a step back, because you truly don't understand.
Sometimes after I have classes for six consecutive hours where I'm constantly surrounded by other people, I literally have to come home and lay on my floor and shut out the world. It's like I've been overstimulated for so long that I just can't function, and I need to recharge with solitary peace and quiet.
This means eating alone is ok. Not going to social events every other night is ok. Putting headphones in to show others you don't want to talk is ok. Leaving the room to go somewhere quieter is ok. Nothing is wrong with being by yourself.
If you're an introvert, you also probably get some extreme knots-in-the-stomach type of anxiety when there's any form of public speaking involved. This anxiety arises anywhere from having to present a project in front of a classroom to going around a small circle and telling everyone what your name is.
And it's not just public speaking anxiety, but anxiety just from talking to other people in general. This anxiety can't always be explained, but it doesn't have to be justified. Introverts are just this way. Sometimes we get a little nervous and a little sweaty talking to you extroverts but this doesn't make us awkward or "weirdos". It's just who we are.
If you're an extrovert and you thought, "well I get anxious for presentations too... why's she freaking out? You ain't special." Well, it's different for us. It's not that "I hope I don't screw up" type of feeling.
It's more like an intense cold sweat washing over your body where you think, "every single person in this room is going to be looking at me, up and down, critically analyzing every move, action, and word I speak. I hope that no one makes fun of me, laughs, or even smiles during my presentation because I can't bear to be in this spotlight where full attention is solely on me."
As an introvert, I hate being noticed. Seems drastic, right? It's really not. I'm fine with being "behind the scenes" or invisible. I don't need people to look at me, ooh and awe over me, or talk to me because they feel obligated. I don't take offense to being overlooked in a crowd, class, or any group of people.
Extroverts usually need this. They like being noticed, they like people acknowledging them, talking to them, interacting with them. And that's ok. But if you're an extrovert, you've gotta respect introverts for not requiring the same.
We're not weird, we're not freaks, we're not hermits. We just get tired. This doesn't mean we don't have friends and don't want to have friends, it just means we require time away from friends and activity every now and then.
So no, I don't "hate everyone" and I don't "suck" for not sitting with you. I'd rather not anyways if you're the type of person to judge another so harshly.