"This is the logical fallacy of equivocation, of the concepts of "trust" and "personal verification".
I haven't "personally" written the code of BitcoinQT. I didn't "personally" create-or-verify The Universe, or the Laws of Physics/Chemistry/Computer-Networking, but I'm comfortable relying on those.
There is overwhelming evidence which I can "trust" without "personally verifying" it. I don't "personally" understand the proof of Fermat's last theorem, but from what I *did* "personally learn" about the-way-humans-behave, I know that, if there were an error with the proof, several individuals would have independently publicized the error, and the the error would start appearing in discussions everywhere.
The same is true for *relevant* errors in the compiler or the hardware (errors that would affect my life somehow)...if they existed, with just a little time they would appear publically. In a way, I "trust" these things because I have "personally verified" that there hasn't been an internet/media explosion concerning problems with these things. I also understand evolution and the nature of economic competition, where life forms and competing-agents seek out flaws in their rivals for exploitation.
All it takes to verify that my Bitcoin version works is a little time, and indeed most people wait a very long time to upgrade their Bitcoin software, if they upgrade at all ( https://bitcoinfoundation.o... ). Attacks do not take place on Bitcoin upgrades, precisely because it is so difficult to get away with one. If it were easier to try, people would "trust" less and "personally verify" more. People might never upgrade at all.
It is an intellectual cop-out to say that because someone doesn't personally know everything, they are doomed to a lifetime of "faith" or "subjectivity". This is the pseudoscientific Postmodernism-nonsense which (thankfully) has long been dead!"