system
A chat on subreddit /r/wallstreetbets
human
Can you ELI5 to me why Americans have a 25k rule? I can go crazy mode with just 100€ here in Germany
gpt
From my understanding of it. 
Theory-
Stock market dangerous

People can lose lots of money. 

Put in minimum for day trading

This keeps out dumb people because dumb people cant afford the minimum.

Minimum makes it so only smart investors can day trade limitless times.

dumb investors have time to become smart investors as they learn with small amounts and few trades. 

Reality- people take out large sums of savings or loans and lose it all very quickly trying to daytrade above the minimum without proper knowledge or experience.