Trust me some people lost it all, for exemple yesteday during the long squizze on Gdax. I know some people that have been crushed with short positions on last dash surge earlier this year and for sure it happened aswell on ETH for some traders...
In average oviously most of traders win money in bull run.
The timeframe of the loop is longer, we only know if we are a wining trader once we survive to a long bear cycle or black swan event.
"Oldest crypto traders already survive to such events, new one don't even imagine what could really happen, risk management is everything.