The reason to let rich people keep their money is twofold: ethical economic activity is positive sum and rich people have shown an ability to generate these positive spillovers, and letting them keep it gives them an incentive to engage in this economic activity in the first place.
The former does not apply to heirs, and the latter only weakly applies.
One effect of wealth is the ability to dictate the direction of development over physical assets in the real world. I've come to realize that the personalities of those who are able to amass large amounts of wealth over their lifetime tend to coalesce around a certain mean that results in somewhat predictable development patterns everywhere I go. These patterns, which are concerned with maximum efficiency and return on investment, result in an overwhelming bland, commercial, "sameness" that is taking over the globe.
As it turns out, some of the most unique and interesting things I observe in the public sphere are owned by trust fund babies who took a different path to development (or just inefficiently left some ancient thing alone to decay). Either way, personally I appreciate this diversity in ownership of the world around me and this observation has changed the way I view the transfer of wealth through generations.
It's a huge mental leap from "I like the output of nepo babies" to "the blandness in the works is due to the psychology of wealthy people".
I would suggest reading more about the history of development and ask yourself why we used to make prettier buildings, but generally no longer do. Rich people have not changed.
The former does not apply to heirs, and the latter only weakly applies.