Here's a two wheel analogy for understanding why investment is so valuable and consumption will eventually eat into your allowance and make you poor.
As a young boy I quickly leaned bicycles wore out brakes, tires, and handle grips. Being of a mechanical mind bore fruit when it came to repairing my bicycles: I could just bu parts and learn to do the work myself. Not only did I like doing the work I saved enough to buy a soda and a frozen candy bar. The time I invested in learning to fix my bike (investment), doing the labor (money I would have had to pay someone else) improved my wealth situation.
Now many people say you shold learn to do something special and trade that specialty to a bike expert is wonderful except I was 12 years old and did't have that many specialties. As America loses specialties to foreign manufacturers all we have to exchange is past wealth whereas Adam Smith would prefer we use future wealth for trading.
The Theory of Wealth and Time I wrote in 1982 and certaintly holding true since then. Here's the link.