This is why we have the term, "capacity constraints." Melvin accomplished those returns in a year where they would have started off with $10B or close to it. The retail investors you know did it on what, $100k? $1M?

The liquidity available to retail investors is completely different from the liquidity available to firms with an 11 digit book. Assuming those retail investors actually have a working strategy, they can basically invest in anything.

If they find alpha in trading some overlooked company worth $100M total, they can deploy all their capital and make an outsized return. If a multibillion dollar hedge fund finds alpha in a $100M company, they can make a great return of 50% on let's say...0.1% of their capital, assuming they can buy 10% of that company without meaningfully moving the price against them.

So you have an 11 digit book, and you have to get an outsized return. You either find tons and tons of these little tiny companies you can buy single digit percentages of, or you win on big bets from a blue chips that can absorb your liquidity. Or some mix in between. Or you expand to foreign assets, or another class of asset that can handle the weight you're moving around. But you are fundamentally limited, and whatever you do has a different profile of risk attached to it. You are also bound by the risk thesis of your firm and what your investors' goals are.

That's not to say all hedge funds outperform retail. A lot of them plainly suck and fail to accomplish their mandate. But this is too uncharitable a take; the liquidity and risk characteristics are completely different. It's incomparable.