> I would happily make money for n-years and lose for one, provided the amount lost was a fraction of what I earned.

Your caveat there often swallows the rule. Many bet on the market and make big bucks only to lose multiples of it later.

Yeah irresponsible people do. But it's not necessary to bet the farm to make a living. Although it's certainly easier to eke a living off a $600k bankroll than a $50k

Many hedge funds and active traders do this every day. Maybe they're irresponsible, but they're the norm.

It’s different when it’s someone else’s farm.

If you set up a stop loss you could make it impossible to lose a huge enough amount on a single trade to wipe put the profit on your prior ones.

all stop losses do is create an order when a certain condition is met (e.g. last trade price is below X)

there's no guarantee it will be created immediately, execute at all, and if it creates a market order you might very well not like the price it does end up executing at

“Stop-loss” orders don’t work perfectly. If the entire market has gone South, you can lose a lot more than your stop-loss says.