Being in your twenties carries with it the notion that you now have acquired a lifetime of knowledge. You’ve made it through your teens therefore you’ve found the wisdom. You’re seeing things much clearer now that you have a degree in something. You also may find yourself often giving advice, because what’s the sense in having all of this infinite wisdom if we can’t share it with those that are younger than us, and therefore far more clueless.
Ah yes, we’ve lived a couple decades. We’ve seen some things. We must know all.