IQ, aka how smart you are, once used to be the biggest determinant of success. 

Then came the EQ.
Empathising with people made us better leaders and effective communicators.

The world evolved and everything around us is now designed to attract our attention.
Thus, making it priceless for the ability to devote our 100% attention without being distracted. 

It’s not the IQ; it’s not the EQ; it’s not their combination either.
The ability to focus is the most significant determinant of success.