Before you have kids you can easily say I won't let my kids do that. And you honestly believe it.
When you do have kids you understand what being a parent is like. You realize that it is harder than you thought.
Before you judge another parent remember you don't know what you would do if you were in their shoes.
You learn that they won't behave all the time so you know you have to pick and choose the boundaries you set accordingly.
When you are a Grandparent you already know that they are only young for a short time and you enjoy every moment while they are young.
And as a Grandparent it is their parents job to be the disciplinarian and you get to be the chilled fun one.
Grandchildren are the reward for being a parent.