Wait until your kids get close to graduating high school... my oldest will be starting college in about 3 years and even though I've been saving since he was born, I still have no idea how I'm going to pay for all of it.
My parents never paid for my college and I Graduated debt free with an engineering degree.
Maybe having to pay for college will cause them to take internships to pay for college.
I was in the middle - my parents helped some - probably to the tune of maybe 20% total of my expenses. I worked multiple jobs, got some small scholarships, took out some loans. A mixed bag, but there was no question in my mind that somehow my parents "owed" me that luxury. they had 2 other kids to deal with as well after me.
I think maybe their kids should consider "not going to college" but that's a hard idea to sell, since it does have a measurable impact on the work and income a person can get.
My total bill was 30,000 USD for my bachelor's degree.