I can easily imagine this - if you're an only child, whose parents are dead and either they themselves were only-children too, or they weren't close at all to their extended family, then someone could find themselves in this position.
@Velveting It's really not that easy. I can see how it could look like that from the perspective of people who already has established friendships, or who've just been lucky, but it isn't. In our society, people aren't that open to making new friends once they get past around 25 years old. They may be polite, but people tend atrophy socially. They become increasingly risk averse and huddle in friend groups that they made at university, secondary school or even primary school, even if they don't have a huge amount in common with those people anymore. If you don't have that for some reason, you could easily find yourself friendless.
People say 'Well why don't you make friends at the gym? Join a class!!'.
Whilst this seems like a perfectly sensible idea on paper, my experience is that it doesn't work as easily as that. Most of attendants of things like classes or workshops arrive as pairs of small groups, and they go there to spend time with each other, not to expand their social circle, so they tend to mostly keep to themselves. You might be lucky to find someone else that's alone, but it doesn't mean they want to also make friends, or that they see you an someone interesting, or that you'll see them as a suitable friend.