live beyond/within your means
live beyond (one's) means
To spend or owe more money than one is earning or is able to repay. They've been living beyond their means for some time now, but they're too proud to move out of that giant house or give up their expensive cars. Being so poor during college taught me from very early on not to live beyond my means once I got a steady job. If you keep living beyond your means, you'll deplete your bank account before you know it.