Too many ETFs

http://www.cnbc.com/2016/10/23/santoli-overcrowded-etf-market-headed-for...

CNBC:  "Because of their structure allowing brokerage firms to create and redeem ETF shares without trading the underlying securities, they are inexpensive to own and tax-efficient. This gives them a dual nature for investors, the way light to physicists is both particle and wave: a highly efficient trading instrument that's also ideal as an inexpensive portfolio to hold forever."