Hustling backwards refers to making financial or moral decisions that end up costing you more than you should have gained. It is a common mistake many people make when purchasing things on credit, taking out business loans or mortgages including other things like online sports betting or day trading.
For example, back in the day, so many cats used drug money to get into the rap game. Nowadays you have got some but not all Hip Hop recording artists who use legally earned money from the rap game to get into the trap game. At the end of the day, if you play stupid games, you win stupid prizes. That's how it is and always will be.