Just that it's easy to fall into a spiral. Also, if you can't move and don't eat out, your food and housing costs are mostly immutable.
Increasing earnings gives you more money today.
Decreasing spending gives you more money today, and more money every time that you act on that same habit. Cutting your rent doesn't just put cash into your wallet now, it also decreases the amount you need to save to live (or retire) at your current lifestyle.