WhatsApp does more security than telegram, i don't know much about Discord but i make use of WhatsApp and the options of securing yourselves from unsupported conversations is free unlike telegram that demands you to use their premium feature. If i don't give out my number, no once can add me up, message me even through groups, i set my restrictions too well.
It is? Im not sure though but there are some red flags when I use whatsapp. Yeah telegram isnt safe either but I think its more used by many, I am using it due to crypto related stuff and communication to some airdrop projects. What I dont like about it its swarming with scammers dming you.
Yes, WhatsApp seems to be more secured since communication there is more to private connections. What exactly are your red flags in WhatsApp?
Telegram is a den for scammers, practical example is when i had issues with funds deposited to my exchange which i contacted the support team through telegram, in less than a minute i received too many support reach, all are fake profiles pretending to be admins, we can find more scammers in telegram than in any social app. If not for joining groups many people won't be making using of telegrams for communication purpose.