How Important Is It Not to Spend Money You Would Be Hurting if You Don't Get Back?

The pair have been in the black every year except one since they started their book business. They say it's important not to spend money you would be hurting if you didn't get back. 'I'm banking all the excess money at this point because i'm already itching to get new covers on my medical roma books, and most of my faassy books need face slips'