Many believe not. And in fact, any study claiming so is skewed because many actively managed funds are actually closet indexers. This happens when a fund is not materially different from its benchmark index.
Even if an investor acknowledges that investing in an ETF involves risk, the next question is whether there is adequate reward, and whether the approach is optimal.
Can everybody succeed at stock picking? No. Success requires experience, education and focus, as well as freedom from the constraints of illiquidity. The opportunity in stock picking really hinges on the question of efficient markets.