

I use SMS specifically because of the network effect. Almost everyone I want to communicate with has a cellphone, so all of them are capable of sending and receiving text messages. There is no need to list my installed messaging apps and compare it to theirs, we just need to exchange phone numbers.
My longest and most active conversations (chatting with my wife or my closest friends) are going to be over a more feature rich app, but if I need to set up a quick chat with 3 or 4 people, I am not going to think what messaging app we all have in common, I will just start an SMS group chat.


All I know about him is that he has a very large YouTube audience and that he does particularly well among young adults. That is an audience that has (a little bit of) disposable income but is still learning how to make good use of their money. I assume Mr. Beast advertised his book non-stop on his channel, so his viewers went out and purchased it.