Assuming myself as a typical bogelhead - an inheritance just means higher net worth and won’t significantly impact my life (retire a year earlier or spend % of increase). If my parents chose to provide an inheritance for both of us in trust as opposed to outright because of the concern of a damaged sibling relationship - I’d accept that % cost on their money as it is their wish. Sure it may be unnecessary but if that’s what the parents believe is required to keep the peace - it’s their $$. I thought that’s the whole point of this discussion - provide options?
It’s hard to not let your personal bias and experience direct your opinion but not every child is like you or has your experiences growing up to shape them the same way. We all deal with our own shortcomings and to me, I’d take a 0.5% decrease for that peace of mind (Vanguard) over the risk of breaking my kids relationship and/or self destructive behavior of getting money before you are capable of management.
If my parents felt the need to set up a trust because my sibling was irresponsible that cost me thousands of dollars in management fees because I had to be given a trust too to make things equal that would be an example of punishing the responsible child because of the irresponsible one. Not a recipe for harmony. I would not do that. Irresponsible child should feel lucky to be getting anything.