It's the sick nature of depression itself that stops people from seeking help.
The fear is the depression; the anxiety is the depression; sense that no one will be interested is the depression; the belief that it's not really worth it because that help is for someone else who deserves it and you don't deserve it is the depression and that you'd be too embarrassed to seek help because if you did you'd be putting yourself out in to the world and saying "oh I'm sorry, I know it looks like I think I matter, but I don't. I thought I mattered to but now I can see what a pathetic laughable error I have made because I don't" is the depression.
By the time you get to this point you don't even consider other people, or what they might be posting about you on FB. Depression is selfish. The illness is selfish. The people who have it aren't able to consider other people because their world has become so small that it only includes them and they aren't able to consider the consequences of, for example, jumping in front of a train because (in their head) a) the train won't even stop, "after all, it's only me"; b) no one is going to be traumatised by it, "after all, it's only me"; c) it's all going to end in that moment, there is nothing else beyond that moment. And more than that, any fleeting thoughts that touched on it's impact on other people would be quickly disregarded as disgustingly arrogant.
FWIW I have very close experience of depression and suicidal thoughts. I know how utterly desperate life becomes, I understand that the knowledge someone has the ability to end it all, whether they exercise it or not, can be the only thing that gets people through the day. And then for some people the balance gets tipped. I understand the absolute wretched desperation that means someone can't consider the impact on other people, not that they don't.
However, if someone else's work day, child care, commute home, commute to work is disrupted for whatever reason, that is incredibly stressful.
Having to grovel to the childminder who's missed a night out because they've still got your child is embarrassing and stressful.
Having to try and explain to a manager at work (who has a million and one other constraints and pressures) why you didn't arrive at a meeting that 12 other very professionals rearranged their work schedules/found cover to enable them to attend is stressful. They weren't there. They don't care why you're late, only that you were and that everyone has been inconvenienced and extra work has been created because of it.
In that case, I think it's perfectly understandable that, whilst having sympathy for a complete stranger, someone can be focused entirely on the impact on them because their's is the only life they're ever going to live.
I wouldn't think it was 'selfish' but I would be mightily pissed off. Wouldn't put it on FB though.
I know this is long. Sorry.