How did the Boomers become so uninterested in their own children and grandchildren?

I am an elder millennial with two boomer parents. I have 3 kids. Both my and my wife’s boomer parents are still alive. Now I don’t feel any grandparent should be used a daycare service but when I was young, if my parents needed a break they would dump us off in our (Greatest Gen) grandparents porch of my grandparents would come over for the evening. This was a very common thing to do back then, for nearly all kids. Now fast forward when it became time for boomers to be grandparents, zilch. My parents, as well as my wife’s parents, have zero interest in watching our kids. I mean zero. My children barely know either set of grandparents because they simply do not want to take any time out of their incredibly non busy lives to be around them. I feel terrible for my children as they will never get to know them before they age out and die. I will someday have to explain their absence from their lives when they are dead and gone. They’ll put two and two together that’s going to be hard knowing your own grandparents just didn’t have the time…

Once I started figuring this out I wanted to know if this was just a problem with my and my wife’s parents, or was this behavior a boomer thing. I started several conversations with people at work who have kids and boomer aged parents. All of them jumped on the opportunity to tell me, in detail, about how their boomer parents would not watch their children at all. How did an entire generation get to the point that they’ve nearly shunned two generations, their children, and especially grandchildren?