Most people retiring with a 4%WR will see their portfolios grow based on historical data and they'll be able to leave their kids a fine inheritance if they want to. Aside from that I think there are many ways to help kids get a solid start on life that don't involve writing them fat cheques. Of the kids I know personally the ones that get everything handed to them are in far poorer shape as people than the ones that have to work for their money. So personally I don't think firing money at kids is actually helpful as a general rule.
I used to more or less believe this, but now that I have a little more awareness as to how many people receive help (because of some of my work), I realize that's not true at all. Yes, the kids that have
everything given to them and more importantly,
are shielded from all consequences of their actions, tend to have bad results. But those are the exceptions; everybody is just aware of them because they tend to be visible and memorable. Lots more people from affluent family get help on things from down payments, daycare/private school tuition for kids, or even just bringing the kids and grandkids on vacation that simply reduce stress and/or free the kids up to be less worried about income when planning their career without any noticeable negative effects.
Also, while people retiring with a 4% withdrawal rate will likely
eventually leave their children a decent inheritance, barring an untimely death of both my spouse and me, any inheritance will be more for potential grandkids than for our children, as our children should likely be close to if not at financial independence by the time we both pass away. Again, there's nothing wrong with that and feeling that I
should do more for them and it would be somewhat selfish for me to stop earning in my prime years so I can "quit" is probably less healthy than feeling like they are grownups and are on their own financially barring extraordinary circumstances. But nonetheless, even though I intellectually realize that, emotionally I still find it a little off.