The article argues that true competitive moats aren’t static walls but dynamic engines built through disciplined, low-margin strategies—exemplified by Amazon’s willingness to accept slim profits. It shows how maintaining and evolving that “engine” is the only way to extend a moat’s shelf life before competitors erode it.

• Bezos deliberately kept Amazon's margins razor-thin, making it a barrier that big rivals like IBM or Microsoft couldn't risk matching without hurting their own earnings.
• In 2007, analysts and portfolio managers mocked Amazon's thin margins as a sham rather than recognizing it as a deliberate moat-building strategy.
• Moats built this way aren't static walls but engines requiring constant upkeep—cost control, process optimization, reinvestment—or they decay, as seen in Anthropic's compute-driven efficiency gains in AI.
• Fat profits attract competitors to invest and invade a market, while low margins deter most newcomers from entering at all.