It is never going to be worthwhile for a personal investor to attempt to beat the market.
That statement looks very iffy to me. I see it as a strong claim resting on a bunch of unstated assumptions and with no evidence to support it (don't forget about the difference between "a personal investor" and "an average personal investor").
Take a look at a graph of the the distribution of financial assets by net worth percentile. The typical share of stock is owned by a person or organization hundreds or thousands of times wealthier than you*. The bottom 90% of investors own together own less than a fifth of all equities, and less than 6% of other financial assets. Your competition in the stock market is not your neighbor -- it's a family office managing $200 million.
If a retail investor with $50K puts in the time and effort to beat the market by 5%, he can make an extra $2,500 per year. ...
P/S/A: There are single sentences which can create life-changing amounts of difference.