At a minimum, 4 years in college. The things required to do the 10gbit router are things you will never run into, learn, or be challenged by bit banging SPI wit

At a minimum, 4 years in college. The things required to do the 10gbit router are things you will never run into, learn, or be challenged by bit banging SPI with an existing Ethernet peripheral. Pretty much by definition, the engineering required for "high performance" anything is completely divorced from the knowledge required to implement basic systems.