I think many people who have children would gladly do 10 year in prison at age 60 if it meant they could leave $400m in their estate. If we pretend for the sake of the argument (unrealistically) that there's no major ethical concern, and that the money can actually be kept afterwards, then I would definitely make that sacrifice for my children. They are more important to me than my own personal comfort.
I would not assume that giving my kids $400 million would be a net benefit to them.
Now to be fair I might be wrong, since I’ve neither researched this nor given it much thought. Maybe there is research on deca- and centimillionaire heirs that shows positive effects of money on life satisfaction, happiness, health and other life outcomes. However I suspect it works similarly to sheltering kids from adversity, failure and hardship in general: disadvantages them psychologically and leads to more problems down the line.
> They are more important to me than my own personal comfort.
Which means you can have a bigger positive impact on their lives by being present than by giving them money.