I'm amazed how many grown ass adults on airplanes act like little kids when it comes to seat belts and basically everything else.

Not just ignoring flight crew advice and common sense to generally stay buckled in order to gain maybe a minor amount of comfort and convenience being unbuckled, but unbuckling even when the seat belt sign is on and again common sense says being buckled in is the smart move. On my most recent flight I heard quite a few people unbuckling their seat belts while the plane was still rolling down the runway after landing. You couldn't wait 5 more minutes until the plane is at the gate?