Floating-point numbers start behaving more and more like Infinity the bigger they get. The bigger x is, the more y there are such that x + y = x. Then x hits Infinity, and we have x + y = x for all bar NaN.
Don't mind me, I'm just learning about the properties of the basic arithmetic units of computers, like, a decade into my career.
(It's actually all bar NaN and -Infinity, but that doesn't sound as neat.)