In economics people study how the wealth of a nation is produced, consumed, and transferred. When a person studies economics then they specialize in this area, and they may decide to go into government or politics as a result of this decision. All colleges offer some type of course on economics, and some even have several classes that study certain aspects of economics in more depth.
The government is neither a monolith nor simply the public interest personified
The petty economics of the rich are just as amazing as the silly extravagances of the poor