Almost all programmers work in frameworks or on top of a large pile of abstractions. I e.g. talk about web frameworks, database frameworks, cryptographic libraries, graphics programming toolkits...

To become great, look what's underneath each abstraction and see how many layers down you can go and still understand stuff. Try to build your own abstractions from the ground up, e.g. write an ORM, write an interpreter, a network protocol, a graphics toolkit, a Javascript framework.

That will already propel you into the 95-99 % quantile in terms of technical understanding. I see e.g. so many frontend people that only have a superficial understanding of how Javascript or a browser works, or how to write good CSS from scratch.