The Signal messenger and protocol.

Not sure if any of you have encountered the same resistance to using Signal. Some of my cousins refused to use Signal because they are already using "too many chat apps" (e.g. WhatsApp, Facebook Messenger, WeChat, Telegram, Line, Snapchat, etc.). To them, Signal will just be another chat app among their numerous other chat apps. I understand that jumping between so many messaging apps imposes some kind of cognitive and maintenance burden. What are some ways to convince such people to use Signal?