Well 'bubble' is not defined by whether the industry's products are valuable (or we would never have a 'housing bubble')—I would base it on whether investors we

Well 'bubble' is not defined by whether the industry's products are valuable (or we would never have a 'housing bubble')—I would base it on whether investors were putting too much money into a type of business. There were so many Uber-for-X startups going under that former YC President Sam Altman wrote this post on unit economics: https://blog.samaltman.com/unit-economics https://blog.samaltman.com/unit-economics