think this way.
Congress borrowed money - (from retirees, employees, etc). Used the money. when it is due with interest, congress renege on it. all these people are gonna be angry because money was taken out and now congress is reneging to pay. plus there are lots of businesses that depend on retirees - medicare, medicaid etc. these businesses may have to close creating chaos in employment. military will not be fully funded, and contractors will stop work. It'll be chaos.