When you already have a few hundred million in stocks, bonds, etc, the marginal benefit to putting another few million into the bond market is completely irrelevant--it's a rounding error in the overall portfolio. But putting those few million into a venture capital fund has the potential to generate a noticeable return.

It can also insulate you against structural shifts in markets. If WeWork were to fundamentally change the global real estate market, or some new battery startup fundamentally changes the energy landscape, investors in the incumbents can be left with significantly devalued portfolios.

Having a piece of anything/everything that might become the "next be thing" is a hedge against that.