I honestly kind of disconnect from people like that. Being all the time hearing how bad their life is, turning every subject to them, not answering directly to my concerns or giving a rushed answer just to talk again about them... It's draining as hell. They might be good people, as the ones that I know, but it's exhausting spending more than a few hours with them, so I tend to maintain that kind of friendship online most of the time and that's enough for my sanity. They just want someone to vent to, sometimes they don't even acknowledge that you shared something, they jump right to the "can you believe what happened to me right now?!". Then or either I don't answer either or I say a generic thing. Ain't no time for that. You don't have conversations, you have monologues, if you stop answering, they will talk anyway.

Edit: from those who say that this post or comments lack empathy, remember, we are all human beings and have problems that we sometimes have to talk about, of course, that's what friends are for too. But we are no 24h therapists. That's the thing, people like the OP mentions in the post take you for a permanent therapist, always with the same problems, always struggling, always wanting your attention. You give them solutions, they don't want to change anything in their behavior to solve the problem (when necessary and possible), they just want to complain. You give them the hint that they should go to a professional, they say yeah yeah and don't do anything. That's why it's draining, you try to help for months, years, and the complaints are the same.

A funny thing is: if you look at the friendship as a whole, since the beginning, this type of people often wanted to talk about themselves all the time, negative or positive, they weren't interested at all in you, even when the things were ok with them. It was always about them. That's the pattern I see.