To be "spurred on" is to be motivated to do something. He was motivated, or driven to perform his duties by something (in this case, the ability to make money). That phrase actually comes from the spurs on a cowboy's boots! A cowboy wears spurs, or little, pointy metal spinning disks, in order to poke his horse in the side to get the horse to run (or gallop). So, when a cowboy "spurs on" his horse, it means he wants to motivate the horse to run. Hope that helps! Good luck!

It means 'motivated by'. He was motivated to work hard because he expected to be well paid.