WhatsApp, a Messenger app that have become a default in some countries for daily communications. The lack of understanding from users is evident, but in my experience is more than ignorance,

is resignation, you explain the risk, they understand but keep using it for convenience or "need", choices, bad ones

https://www.trendmicro.com/en_us/research/25/j/self-propagating-malware-spreads-via-whatsapp.html