I've had the sense that growth investments are almost completely closed to the public in the United States. This trend has been gradually solidifying ever since the dot-com bubble, and has reached its logical conclusion today. The only IPOs happen when companies reach 100-billion dollar valuations, and sometimes not even then. IPOs seem more likely for private companies that have lost their growth potential.
There's certainly some potential for growth and returns still available when companies reach this stage, but the lion's share is taken out already. The index funds are also often at the ass end of this phenomenon, buying in only at very high valuations. The most absurd example happening a week ago, with Tesla entering the S&P500 as the sixth biggest company.
I'd like the possibility of investing in a fund of unlisted companies. The growth sector that's not represented in the major indexes is far too big to ignore. I try to compensate by having a portion of my wealth in "small cap" companies, but there is still a very significant sector that's completely missing.