What else busdines does Meta have beyond FB, Instagram, Whatsapp?
I guess they are somehow wurnelable to search market problems(including regulations), but that won't make them collapse, just less wealthy. And they can start monetizing WA and Insta more agresively.
Perhaps your concerns are one of reasons why they are investing so much in metaverse.
Google on other hand has bigger hold. They have Hosting business(which is not profitable currently, if that is truth), and YouTube. If something happens with search business, YouTube would feed Alphabet. Also money from play store and licensing fees from android vendors. I bet, Google's investment in Android was great move. It makes them more secure than Facebook.