What is the fundamental factor that determines whether you can make a stable profit in the career of affiliate marketing?

When I browse the forum posts, I find that many experienced affiliate marketers often struggle between profit and loss.

I believe they have mastered the basic skills of affiliate marketing and can proficiently use various tools.

Therefore, I have to think about a question:

What is the fundamental factor that determines whether you can make a stable profit in the career of affiliate marketing?

Is it constantly evolving alliance marketing skills?

Or the quality of advertising network traffic?

Or depends on whether you can find profitable offers?

Or is it your advertising creativity? Such as the combination of LP and