Those damn millenials

Pretty much. And the older you get the more it is so. Get old enough and 30-40 year olds will seem like kids to you. We must keep in mind not all experience or personal change is an improvement. On yourself. The mutually true and conflicting facts are: the more experience you have, the more basis you have to be certain in your opinions and; experience is relative and fluid. The more certain you are in your views, the less open you become to new information and change. Thusly as you accumulate age and experience, without openness, the chances your experience becomes out of alignment with objective reality increases. In other words it’s a fine balance between relevant insight from experience and having your perception of the present warped by applying assumptions based on past experiences which have been invalidated by changes.

what about between a 15 yr old and a 30 yr old

Yes, there's a difference between 15 and 30