In my case, for example, most of my friends are not born americans but rather people that lived in south america that moved to the US or still live in south ame

In my case, for example, most of my friends are not born americans but rather people that lived in south america that moved to the US or still live in south america. In Colombia/Vzla EVERYONE uses whatsapp. At first it was because SMS has charges per text sent so a free, better way to communicate (whatsapp) quickly became the norm. Network effects pushed through boundaries and now I use it more than anything else to communicate with friends and family. I have groups with my immediate family and with friends across borders. Mind you, I've lived in the US most of my life so I use iMessage with all americans and whatsapp with the rest. I think it comes as a surprise to most people in the USA because here we never had to deal with SMS charges (plans were for the most part unlimited). In other parts of the world, the opposite is true, which is where whatsapp gained it foundation. Add to that cross platform, free, awesome ux, network effects and the fact that IT WORKS PERFECTLY and boom, 19B. Cheers.