That was the nature of the dotcom bubble. Bandwidth costs back then were exponential, whereas revenue was linear. The chatbot bubble instead has the problem of needing to manufacture demand. Different mechanisms to the same results.

I’m not sure that’s an accurate or defensible perspective on why they failed. From Wikipedia:

Pets.com lacked a workable business plan and lost money on nearly every sale because, even before the cost of advertising, it was selling merchandise for approximately one-third the price it paid to obtain the products.[22] Pets.com tried to build a customer base by offering discounts and free shipping, but it was impossible to turn a profit while absorbing the costs of shipping for heavy bags of cat litter and cans of pet food within a business field whose conventional profit margins are only two to four percent.[22][23] The company hoped to shift customers into higher-margin purchases, but customer purchasing patterns failed to change and during its second fiscal year the company continued to sell merchandise for approximately 27% less than cost, so the dramatic rise in sales during Pets.com’s second fiscal year only hastened the firm’s demise.[22]