The part you're missing is that the people who hit those bullet points probably weren't always that way. In my experience they usually had very bad social experiences that drove them to isolate.

That isn't necessarily an excuse. I strongly believe that after a certain point it's really on you to get over your hangups, especially if you're an adult. It may not be easy but it's necessary

Anyways, I've never found that just telling lonely people "it is your fault you're alone" has ever been helpful