There's a measure of game theory here too. If Google didn't hop on the AI train, people would use ChatGPT or Claude to fill the Internet with slop and 10-blue-links Google would cease working anyway (which it kinda has already). So their only option is to hop on the AI train and disrupt themselves, lest they be disrupted by others.

It's very much a Prisoner's Dilemma. Legacy search and the open Internet was an equilibrium that only existed while the majority of people co-operated. Once you allow an individual actor the ability to create large chunks of the Internet, it dies. Your only option is to be that individual actor.