Just some random thoughts.
Literally:
Unlike some animals, humans won't survive for very long alone after being born. So the phrase would only apply to a few 3 day old babies whos cognative abilities are to underdevelopped to make sense of the situation. Makes me wonder in what sense the condition is 'horrible'.
Perspectively:
Feeling lonely, feeling like you are born alone (no family ties, bad upbringing) and die alone (no friends, no one that cares about you.), then you have to wonder whose fault that really is. Humans are in most cases social creatures, even in the worst of scenario's, it is unlikely you won't be able to find anyone that cares unless you isolate yourself completely. If you isolate yourself completely, one has to wonder if that is perhaps what that person wants.
If you want to socialise, but isolate yourself, you'd have to be seriously masochistic.
If you don't care about socialising and isolate yourself, you have no friends of ties to other people. And end up dying in the process. Then there's nothing sad about that. It has clearly been that person's choice. Not every person is the same, some people truely enjoy being alone, living their lives on their own terms. You could say that that is actually something beautiful. If only everyone could live their lives on their own terms, what a potential paradise that could possibly be. (ofcourse that's not possible because indirectly, certain peoples way of lives will influence other peoples ways of life in a negative manner, making it impossible for everyone to live their lives on their own terms. But still, the idea is inspiring.)