Well, is there anything stopping me from planning ahead for the sudden loss of a support network, even if I believe myself to have one? Is there anything that says that I could not quickly adapt to a situation where I am cut off from my support network? I already think very frequently about all sorts of questions that would lead to such a situation, and I try to plan accordingly with various redundancies.

So this question really just boils down to "How well can you handle isolation in a pinch?" — those who can handle it well might prefer to live in mental comfort for as long as possible, but those who do not believe that they could handle it well, might rather prefer to have more time to mentally prepare. I don't think that either is strictly better than the other, as those who live knowing that they have no support probably do get used to it.

But how exactly would this question play out in practice, anyways? Would some Morpheus The Matrix figure tell me that people would not have my back during some non-specific future crisis, and then he'd ask me whether I'd like to take a blue pill to make me forget the whole experience? Well, what's the difference between that and, say, a dream or hallucination wherein I received a vision of the future, and then I didn't heed its message even when it was later proven correct? — Morpheus' words would be "for real", sure, but a hallucination would feel like it was "for real" as well, many people even take their dreams very seriously.

Which is to say, on the one hand, what is the difference between wrongly believing yourself to have support, and choosing to disbelieve in a dream or drug trip; and on the other hand, what exactly is the difference between "knowing you have no support" and wrongly insisting that you have no support even when you really do?

The only way to truly know when you have no support is when the crisis itself comes. Until then, it's perhaps best to be cautiously optimistic.