In my personal experience, “the really old colleague” is often a real throw of the dice between stubborn-as-fuck-never-matured-know-it-all and very-interesting-seen-it-all-genuinelly-mature-colleague - so basically opposite ends of the scale.

If you’re early career, having one of the latter kind of older colleagues is probably one of the best things it can happen to you, especially if you’re a bright kid.