Hey! Shy introvert here!
Being an introvert means that I get pretty tired talking to people. I'm not mad and I do enjoy being talked to, but generally, I'd rather be watching Netflix or reading a nice book while eating some soup.
Plenty of introverts have friends, and even enjoy them! We just get tired easily. Having conversations is difficult.
I'm also shy, which doesn't let me talk to a lot of people. I don't have many friends because of this, but I have a few close friends who I really enjoy. I think I worry too much about what people think of me, and how I talk and think (I have a strange sense of humor and speech problems).
I don't judge people who don't have friends, because some people just want to be left alone! They could also have underlying problems including depression and anxiety, and truth is, it's sorta hard in this day and age to make friends.