I have said before, and I will say again: The Bogle approach is better than most investment strategies, but that does not mean it is better than any investment strategy. Some people want to manage their own investments, and some of those people will do better than the market.
I have seen the stock market do too many stupid things during the decade I have been following it closely to believe that it is always right. I have seen bargains go a-begging, and I have seen bubble stocks float up to ridiculous prices. The market and individual shares do not move in smooth, gradual progressions.
Other investors will do almost as well as the market with a lot less risk. Talking about infinite investment horizons, as Bogle does, is fantasy. Most people have bills they need to pay even when the market is down.
For people who want to manage their own money, ETFs can be simply superb. Among many benefits, they offer a low-cost way of betting on an entire sector or an asset class. They can be much better than the most common alternative, which is buying individual stocks. And you get to choose among a wide variety of ETFs, because there are multiple companies offering them.
For example, Vanguard offers an index mutual fund that tracks "mid-cap growth" stocks. That's the kind of asset class I consider to be a joke. On the other hand, you can find ETFs that will track things such as inflation-protected bonds, the Singapore stock market or gold. These can be really useful.
(Vanguard, which is no longer run by Bogle, also offers a family of ETFs, although regular index funds still account for the bulk of its business.)