&gt; To illustrate the difference, consider what would happen if the Warren Buffetts and David Teppers of the American capital markets put all their money into ETFs. You&#x27;d have no price discovery. Someone needs to be wiling to do their own research, reach conclusions with conviction, and trust in those conclusions through short- and medium-term wobbles.<p>There are a lot of different ETFs, some much more broad than others. You don&#x27;t need to buy the whole market. If you think energy is cheap you can buy an ETF of energy companies (say XLE) which is a useful way to diversify if you&#x27;re not able to buy reasonable quantities of multiple names.