Because we're still in the "get them hooked" stage where AI startups and Google/Meta are losing money on AI.

Once they start properly monetising (aka making users pay for what it actually costs them to train and run), it will be a different story. The vast majority of people won't pay $20-30€/month for an LLM to replace their search engine. (And an analysis I saw of OpenAI's business model and financial indicated they're losing money even on their paid tier, per query).

IMO the AI players are only hooking the power users and technically inclined (in regard to AI replacing search), but there's a long, long tail of people who are going to be using Google as their search engine until the end of days. Think the type of person who types "facebook.com" into Google instead of their address bar — they're not switching over to ChatGPT or Kagi any time soon.