How do you know if you can trade full-time?

Seeking expert guidance, what is the difference between left-hand trading and right-hand trading?

I resigned yesterday, due at the end of the month, I want to do trading full-time, but I don’t know how far this road can go?

How to understand the phrase "the simpler the trading system, the better"?

What is the degree of simplicity here? Or the simplicity here is not what I thought, just use a few indicators, so what do you think of this sentence?

Winning ratio and profit-loss ratio, which one do you value more?

If you have a bad mentality, does this mean that you are not suitable for trading?