This article serves two purposes. Puffing up currently wealthy people as only being that way from pure grit and determination. No inheritance here. If you're wealthy it's because you've worked hard for it because we've already established that inherited wealth is a losing proposition.
Secondly, it tries to establish that there is no generational wealth which reinforces the first premise that all wealth is due to hard work. It's a wonderful bit of circular reasoning. All wealth is gained through hard work, generational wealth might exist but it's fleeting, so the multigenerational wealth that you do see must be due to multigenerational exceptionalism.