In the past whenever I've seen people talk about being lonely I would make an effort to reach out to them.
Not just tell them they're not alone, but offer to talk to them. A typical example would, in chat, be when people say, 'I have no friends,' I would say, 'I'd like to be your friend. Lord knows, I need friends.'
And you know what?
It's always been a waste of time. For whatever reason all these lonely people don't actually want to take a chance on someone who is reaching out to them.
When I have the resources, I keep trying, because I'm lonely enough to take that chance.
However I'm starting to suspect that people complaining of being lonely are either 1. Not really lonely in any absolute sense, just complaining about a temporary situation or 2. Lonely precicely because even when someone else reaches out to them (I mean in most cases if you want to meet people you need to be the proactive one) they can't be bothered engaging.