We were already FI (& 45) when our son was born & were concerned about how we were going to raise him to be a responsible, fiscally knowledgeable, & nice guy. He's 24 now & I think we succeeded. It boils down to expectations & coaching. You need to be hands on now, not later.
Early on, DS had a modest allowance & was expected to use it instead of begging us for stuff. It was amazing how his wants became much less when it was his money he was spending. Sadly, most of his classmates were getting unlimited handouts whenever they went anywhere or did anything extracurricular. DS learned how to save for what he wanted, & we helped him to value shop but allowed him to make mistakes. Later on, though his school work was his primary job, he was expected to do household jobs, including doing his own laundry, cleaning his room (not just clearing clutter), taking care of the dog, & helping with meals. By age 14, he earned the BSA Eagle scout award (his idea). We expected him to work summers from high school on, to manage a checking account with no overdrafts at age 15, to manage a credit card paid off in full every month from his checking account at age 17, & to fully fund an IRA out of his internship earnings during college summers. We paid what his university charged (beyond the merit scholarships he received), but he was expected to cover anything over that. When he had to live in an apartment his sophomore year, we paid a basic room & board allowance once a month -- he was expected to make it last or pay any shortage. He usually saved some of it by cooking & not partying. He started using YNAB after graduation. At this point he's asking us for investment & tax advice.
As he grew older, he could tell that we are financially secure. We've taken him on some incredible vacations, but if he wasn't interested & appreciative, we wouldn't have done it. In other words, we tried to always present travel & family activities as learning experiences & not entitlements. We have never told him that "someday what we have will be his" -- my grandparents did that with my father & it sucked all motivation out of him. Ironically they never had a large estate but he didn't realize that. DS knows that he must manage & grow his own stash independently of what may or may not happen with our estate.