I came across a small business: a product priced at 28 yuan, selling 7,000 units a month, with net profit estimated at 20 yuan per unit—that’s 140,000 yuan a month.

Numbers like these are easily mistaken for “huge profits,” when in fact they come from getting three things right at once: product selection, supply chain, and advertising. A price of 28 yuan means gross profit depends on volume, volume depends on advertising, and advertising needs to deliver ROI.

The real challenge isn’t finding a product that costs 28 yuan. It’s finding one that people are willing to buy a second time at that price.

Repeat purchase rate is the real story behind the profit and loss statement.