That assumption relies on two uncertainties:
1. The probability of discovering something in all that binary code, especially with the intricate and non-orthogonal nature of x86/x64 assembly and odd compiler optimisations. This isn't some 80's game.
A comparison:
28500000 = Chrome binary size [1]
750000000 = Human Genome size (converted to bytes - 1BP = 2bits so 4BP per byte) [2]
So we're only 26x more complicated than Chrome and we have absolutely no fucking idea what is going on with us most of the time.2. The probability of a vulnerability being published to Google versus selling it on the private market.