I have to assume you're not trolling, and really can't conceive of an entire large category of people who might, in response to a Facebook post, follow step-by-step instructions to change their default search engine without understanding the ramifications thereof, or how to change it back.
There are more people in that category than in the category of people who change their default search engine for good reason, knowing that it may deliver a less-optimal experience than Google under some circumstances.
Interacting with humans has shown me many, many examples of people who can follow steps written by a marketer to push their nonsense without any clue of how to reverse the process.
What doesn't make sense is believing that every human being is always intelligent and rational and never forgets anything.
I have to assume you're not trolling, and really can't conceive of an entire large category of people who might, in response to a Facebook post, follow step-by-step instructions to change their default search engine without understanding the ramifications thereof, or how to change it back.
There are more people in that category than in the category of people who change their default search engine for good reason, knowing that it may deliver a less-optimal experience than Google under some circumstances.