The vast majority of the companies in the world would be driven to bankruptcy if everyone was as serious as I try to be about boycotting.

No, they would just not engage in madness. If you make it more costly for them to do A, whatever A is, they will be less likely to do A.

That's without considering what a society of people who trust hardly anyone

So called low trust societies don't work very well. That said, I think a healthy mistrust of humanity is a pretty good thing. Humanity is fallen, after all. If anything, I would say your mistrust is too limited.

and the obvious effects on reproduction.

That is a real problem, yes.

Maybe I'm over-thinking it.

A common theme.