Venture capitalists have dumped crypto and moved on to a new fascination: artificial intelligence. As a sign of this frenzy, they're paying steep prices for startups that are little more than ideas. 

Thrive Capital recently wrote an $8 million check for an AI startup co-founded by a pair of entrepreneurs who had just left another AI business, Adept AI, in November. In fact, the startup’s so young the duo haven’t even decided on a name for it. 

Investors are also circling Perplexity AI, a six-month-old company developing a search engine that lets people ask questions through a chatbot. It’s raising $15 million in seed funding, according to two people with direct knowledge of the matter. 

These are big checks for such unproven companies. And there are others in the works just like it, investors tell me, a contrast to the funding downturn that’s crippled most startups. There’s no question a new bubble is forming, but not all bubbles are created alike.