>Thought experiment: who can buy the most shares of others? And if they buy "well", how does the distribution of wealth shift?
It shifts to the sellers, not the buyers. That's because buyers are competing with each other which drives the expected return close to the general market rate.
Assume there's a magical oracle that tells you: this kid will generate $100M of wealth over their lifetime - to not get bogged down into discounted future value, lets say the risk free rate is 0% - but needs $500k for education and resources early.
Without any investment the kid will become stuck in a local maximum in a shitty environment and generate $100k instead.
Market competition will bring the total sale amount close to 0.5%. Lets say it's 1%, although that's very high. Funds bought shares that are 'fairly' worth $1M for $500k, for a profit of $500k - not bad. The person gained $99M. Total distribution of wealth becomes more fair, not less.