There are some folks who don't have any other source of income, so they have to live off their trades, and even if they can figure out ways to be profitable, it becomes even more difficult if anyone believes that they are going to live off of their trades - and especially if they don't even have a lot of capital with which to work.
In as much as I don’t agree with some things about traders that you said I will say this is spot on, I have always been an advocate that should you be a trader today and putting in efforts to get the knowledge of trading like technical analysis and fundamentals with others i will say apply same energy to getting large amounts of funds to trade, people will say once you have risk management you can start with little capital, yes i can’t debunk that claim but over many times it is usually hard to grow the kind to any substantial amount. The traders with even more funds to trade or spare easily have better trading plan like holding trade during loss or allowing to hit the TP than those who have little funds. So even extra source of income is definitely needed rather than been a full blown daily trader.