Rome prospered tremendously and the population grew to where housing was limited and prices went up on everything including food. People's lifestyles got to such a point where there wasn't much desire to work lower income jobs nor was there enough money in it because of their cost of living. They then found people from outside their large cities (immigrants), to come in and do the work but since the workers couldn't afford to live there they established their own communities outside of the city.
The citizens of Rome gave them their money to take care of the labor and the workers went back to their communities and spent it on clothing, food, housing, etc. They couldn't afford to buy such things in the city but they had created their own small economies where they lived. With this in mind, the money the citizens gave them to do the work, left the Republic and didn't come back to refuel their economy.
Slowly but surely, the money seeped out, but back then they didn't have large pools of money to borrow from (like the U.S. is doing), so eventually the citizens began feeling the pinch because less money was going around and around in their economy (known as GDP), and they didn't see it coming. More and more people began spending money on needs not wants so people were being put out of work (citizens and immigrants), and became dependent upon government; a government with ever decreasing tax revenues because more and more people became unemployed.
Of course eventually Rome fell partially because they could no longer afford their militaries so they began losing a lot of territory that they had won which once again meant less tax revenues were coming in. What's worse, the citizens no longer enjoyed the protection they had before nor were they proud Romans anymore which had a lot of negative intrinsic affects.
There's only one thing that has kept us out of this scenario and that is we've taken on a massive amount of debt to keep our economy going. We aren't paying down this debt and eventually the money will stop coming in because we won't be worth the risk. Think about if you kept lending someone money and they paid you interest (nothing else), and then kept asking for more money; would you get nervous?
The money that’s seeping out of our economy because of illegal workers sending so much money back home is being replaced by the Federal Reserve printing more money. If this were a good idea, the Federal Government would print money all day long but they're afraid to do this because they know the consequences.
We're in trouble but the last thing the Federal Government wants is for us to be afraid and start challenging them on being fiscally responsible. This is why they keep us distracted about so many other issues like gun control. I hope the history books won't reflect someday the fall of the American Empire. Send a note to your legislators asking them to send you a copy of their ideas on paying down the debt; they work for you. Thanks!