Basically, you need to first be close enough to help in the first place. Just showing someone you care is nice, but online comments and assurances can only do so much when the person is actively suffering.

Sadly, it usually comes down to money in one form or another. If they can't cover medical and living expenses, and believe they will be unable to work, and left to rot alive on the street, they will just cut their losses.

If they live with chronic pain, or some other awful disease, again, money would help (painkillers, not worrying about work on top of that, and having time to cope and distract yourself). But just knowing that they will never be them former selves again, and that they will live for life with the condition, is usually enough for them to end their lives, and it is very hard to keep them from the brink.

Most people are social, and some will actually kill themselves out of despair, if they feel no one trully cares about them. So, these people not only need a friend, but obviously would benefit greatly from therapy.

One thing I noticed consistently, is that society is usually structured in such a way, to take anything worth living for from people, then someone comes along just long enough to pull them back from the brink, leaving them in the same conditions that made them suicidal. Then it's baffling when they do off themselves.

If we really want people to live, we need living conditions for them. But there is a massive discrepancy in what we say we believe in, and how we actually treat people. For example, we believe in equality, but very much look down on rural, low-class people, associating being born in a poor region with MAGA.