"Is it possible to make a living from trading?"
Every transaction is a trade. Any baker, grocer, gas station owner, cabinet maker, electrician, car salesman, you name it most likely trades something of value for federal reserve notes and makes a living from it. Most trade their time and "skills" working for some employer in exchange for cash, that is their daily trading.
Can you make a living from trading gold, oil, copper wheat, corn, stocks, currencies ect?.... Sure........ but like anything else you need to work hard and make it your specialization to be good enough to survive and thrive.
Most that make a living from some type of market knows that market inside and out.
Just like a realtor or builder needs to know housing market and their local area like the back of their hand, you need to find your niche in whatever market you want to thrive in ... otherwise you won't make the cut just like any other business .
In business you buy wholesale prices, and sell retail prices . buy low, sell high