> 3. Sure, arbitrage exists. But again, who is going to be more likely to discover opportunities for arbitrage? An institutional investor or a stay-at-home mom?

> 3. Sure, arbitrage exists. But again, who is going to be more likely to discover opportunities for arbitrage? An institutional investor or a stay-at-home mom? Not every possible arbitrage is suitable for every market participant. But IMO it's more dangerous for the layperson to fall for the "picking up pennies in front of a steamroller" situation. They might be profitable but not assessing the risk involved in their trades and then (for them) all of a sudden they are no longer profitable.