There are two scenarios that realistically goes down and neither are something I fantasize about:

1. I am the last man on Earth as in the only person left. Everyone I care about is gone, I am alone and doing what is needed to survive by myself is a nightmare. Any current or future major medical issues probably go mostly untreated.

2. I am the only man on Earth. Women haven't been wiped out. About half the people I care about are gone. Humanity realistically isn't long for this world due to the severe genetic bottleneck that would result. And while this would likely not be as bad as only 1 woman remaining in a world full of men, itd still be bad for me and anyone I was romantically interested in. And even if somehow things didnt immediately become forced breeding stock nightmare fuel, I don't want the whole planet's attention on me.

I dont fantasize about being the last man on Earth. I fantasize about having enough financial security to be able to persue my interests without worrying about what I will do for a living.