舍本逐末 (shě běn zhú mò): To focus on trivial details while neglecting the essential — Meaning & Stroke Order

He spends all day studying how to save money but doesn't think of ways to earn money; that's truly neglecting the fundamentals for trifles.

When making decisions, you cannot neglect the fundamentals for trifles; you must grasp the core of the problem.

The company only focuses on packaging while ignoring product quality; it's simply putting the cart before the horse.

He spent all his savings on renovating the house, but then had no money to buy furniture; that's really putting the cart before the horse.