Why do people keep telling me what they think I meant to say, instead of responding to what I actually said?

Because your post lacked empathy or a recognition that the person you responded to might face genuine issues, and because you came across as believing the solution was simple and at hand.

Instead of saying "do you not have any friends of friends? ", try "Yeah that really sucks. I struggled with it for a long time until by chance a friend of mine introduced me to someone and we hit it off. But I hope you have a happier time of it in the future."