You're looking at this the wrong way.
LLMs are difficult to monetize in isolation, but are existential for information technology companies. This is why Big Tech. is so heavily invested in them.
If Google fell behind on LLMs, Open AI could easily dominate search - and thus advertisement, marketing, etc. All the services that literally prints money for Google and which allows them to rent seek globally. It's all about the control of information. People will not use traditional search if they could get a LLM to go out & get that information for them, complete with sources & concise summaries; and when that becomes the new normal, then all advertisement will need to go to the LLM platform, not traditional search.
Think of LLMs not as a new revenue source, primarily, but as new table stakes for existing information technology companies. It is a threat for those who fall behind, not a benefit for those who are in the lead. It's not like embedding Gemini in Google Search will drastically increase advertisement revenue. But not embedding Gemini in Google Search risks drastically decreasing advertisement revenue as advertisers move to LLM search providers.
Disruption is the name of the game. It's a "keep up or get out" situation. This is also why one of my hopes for the LLM industry in China is that Baidu gets displaced by a better Chinese company - the opportunity will definitely be there if Baidu falls behind, which is likely since they've been soft for a long time.