Installing an app isn't the problem. Getting everyone else to install the app is the problem (and their choice isn't "app or money", but "install app and switch everyone over or just exclude/mock the weirdo with the low-class phone"). If you're somewhere where everybody is on Whatsapp/Facebook/... it's similar struggle with people to switch to something else you prefer (e.g. for me iMessage never was topic because just not enough relevant people had iOS for them to build an expectation that everyone has it. But there was a phase where getting people to accept that not everybody has Facebook was kind of annoying)