There are numerous ways to accrue travel rewards fast, and many people will fall into more than one of these categories.

Daddy Warbucks Type A: You buy expensive flights and book expensive hotel rooms which earn exponentially more travel rewards than booking cheap flights and accommodation.
Daddy Warbucks Type B: You spend tons on credit cards organically, whether that be personal use, through your business, or both.
Manufactured Spender: You figure out ways to increase your spending for a fee that doesn't outweigh the value of the rewards you're earning.
Road Warrior: You travel for business, get to charge paid