trading statistics

I'm wondering what groups win and what lose in total.
Small private traders vs. institutionals, big CTAs, brokers

so I looked at some numbers and concluded that average traders
invest ~$5000 and lose 30%-50% of their money to the broker
per year.

I have no idea, what's the total, whether they make profit from their trades
besides the fees,spreads , but this is zero sum and CTAs in total
are profitable , so I assume that small average traders are
almost balanced.
So there remains the ~40% that they lose to the brokers per year
and you have to wonder why people continue to trade and how
the brokers succeed to recruit more money every year and are growing...