Fundamental analysis

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?

Tell me how hard you have worked to make money in trading?

A handful of bitter tears, I have been trading for five years, and I still lose money, what should I do?

In trading, how to solve the problem of being hit by the market back and forth with stop loss? What is the basis for the solution?

How to effectively find the entry point?