it is only insane if you do not understand how Amazon makes money.
If a retailer wants to double its revenue, there are two basic options. Double your margins. Or double your volume by cutting the time you hold inventory in half. Amazon has aggressively gone for the second approach, and is glad to cut its margin in half in return for tripling sales.
Your "comparable companies" are not in the consumer retail business. And if they tried to maintain their margins while competing head on with brick and mortar commodity retail stores, they'd go out of business.
If a retailer wants to double its revenue, there are two basic options. Double your margins. Or double your volume by cutting the time you hold inventory in half. Amazon has aggressively gone for the second approach, and is glad to cut its margin in half in return for tripling sales.
Your "comparable companies" are not in the consumer retail business. And if they tried to maintain their margins while competing head on with brick and mortar commodity retail stores, they'd go out of business.