Successful people, in all callings, never stop acquiring specialized knowledge related to their major purpose, business or profession.

Emphasis on specialized knowledge.

General knowledge is often not nearly as valuable as specific knowledge.

Some of my favorite resources for entrepreneurial insight are:
Jeff Bezos
Paul Graham
Seth Godin
YCombinator
Ben & Andreessen Horowitz
Peter Thiel

If you have any resources to add to this list, I’d love to hear them!