This assumes there aren't any adept retail investors in the public market. There will still be an increasing number of savvy retail investors who will now be inhibited from investing in one of the most symbiotically valuable relationships in an economy, one between young organizations in need of capital and public investors looking for more relevant early investments. Instead, the growth of the private markets will dilute these investment opportunities for the public and now offer them to already rich investors. Shouldn't organizations and economies work to provide more integral investment opportunities to the general public instead of increasingly reserving these for the fortunate few?
I'm not sure that is the case. For every amazon, there are thousands of pets.com.
Now, amazon did make a whole lot of money, so I could be wrong; compiling reliable statistics from private companies is notoriously difficult. Personally, I think this lack of transparency is going to push the market more towards focusing on getting money from investors rather than on actual profits.