In most cases they don't make enough in the first place. They should focusing on making more money first.
This basically. They usually fall into two categories.
The Working Poor/Middle Class (Collectively Worker Class)
or the Dependent Class.
The Dependent class I will touch on just briefly. They get free money from the government and savings are counted against anything they get month to month from the Government. So they have a negative economic incentive that prohibits them from saving and investing. As both will count against their gibs. So what cash they do obtain or earn has to be spent immediately.
The Working Class is a bit more complicated but basically boils down to similar restraints be they Working Poor or Working Middle.
The cost of maintaining the level of comfort to which they are accustomed. That is, the things they value and need. Which are restrained strongly by the cost of things such as the Roof over their heads, the food they buy, and the cost of fuel to get to where they need to be to earn money.
Three of these factors, the Roof, the Food, and the Fuel have exploded in price in the last 30 years. Concurrently, the US Government has removed two from the metric of its analysis on the average year to year inflation. The Food and the Fuel. You would think this was so they can lie about how bad things are, but that is not entirely true. Its because they are legally bound to pay the Dependent Class based upon the average cost of living. The change in Inflation Analysis was done to dodge the legal requirements on the Government for paying its dependents.
Unfortunately, wages have not kept pace with the rate of ACTUAL inflation, through a combination of factors that are way too complicated to go over. At this point getting ahead requires a level of sophisticated knowledge on how the economy, debt, and money velocity works that are beyond most people. TBH, the Dependent Class are responding to the optimum economic incentive. So long as they don't work, they are guaranteed stability at their chosen income level. Which means more and more people will opt to become Government dependents over time.