Yes, that was one concern. pedrocr's reply below (in addition to all the other comments) makes sense - if the current inflow in passive funds is just active fun

Yes, that was one concern. pedrocr's reply below (in addition to all the other comments) makes sense - if the current inflow in passive funds is just active funds being sold and reallocated, doesn't seem too bubbly. Though I am an active reader in the early retirement / Financial Independence blogosphere, and the real life people I talk to (usually nerds) are like 'Vanguard or gtfo'. So it would seem like the average person, and especially Baby Boomers looking for 'safe returns', would think "well, everyone's recommending it so it's all good" and voila, hundreds of billions flowing in. On the other hand my coworkers, most of whom wont read a book to save their lives, are just happy there is employer matching on their 401Ks. I suspect that's more representative of the average population. Not sure the data on this. Also, would the share price of these passive funds go up due to demand enough to cut significantly into returns? Like a 30% increase in share price just because everyone is jumping on the bandwagon takes a while to make up for. (Am I wrong? How much exuberance would it take to bubble up an ETF's share price significantly?) Thanks for all the replies, though. I'm looking for both sides of the argument. The businessinsider article supporting the 'bubble view' was a quick read but too light on substance.