Gas molecules go at an insane velocity, and though they are miniscule, yet there is a LOT of them. Of course, because of all these molecules hurtling around, there is air pressure; yet if you envision a lot of bullets flying around, they don't really "apply pressure": they smash stuff. So why aren't things being destroyed by these mini-torpedoes?

I sense the reason they don't wreck havoc is because they are not coordinated, i.e. they are random. Also things may not work out microscopically as in the real world.