Self-belief is not a fluffy concept. It is the core of everything.
Everything around us, the technology you use, the institutes you study at, the companies you work at, they were all founded on the basis that someone had the self-belief that they could create something that would change how you interact with the world.
Forget upskilling and experience, if you don’t have self-belief you will ALWAYS be limited.
Look at the people you surround yourself with, surround yourself with those that nurture the good in you and erode away the bad.