I work for a quant firm. I am not speculating, but speaking authoritatively - the effects I've stated exist, the specific examples I've given can be captured by retail, and they can deliver outsized returns.
It seems mind boggling that there can be simple effects like this to capture to someone who hasn't worked in the industry, but everything I've said remains true regardless of what you may mistakenly believe
There are more actors in the market than just Citadel. For starters there are day traders at virtually every wealth level and with every level of risk tolerance. Someone is going to claim that free alpha until there’s none left. The notion that there’s so much free, obvious, and reliable market edge simply lying there for the taking by any shmuck with $100 to put into Robinhood is farcical and flies in the face of quite literally all empirical data we’ve collected on the performance of active market participants.