WhatsApp is not that different from a hundred other messaging services, but people pay for it. I have no reason to believe it's worse than the other messaging

WhatsApp is not that different from a hundred other messaging services, but people pay for it. I have no reason to believe it's worse than the other messaging services, but it doesn't solve some fundamental problem fundamentally better, either; it mainly just had good luck with network effects. People also pay for Candy Crush...