Nice story and write up and I was surprised to hear that a WhatsApp group was hacked like how or probably they hack the admins phone and gain access to numbers in the group. Some things I understand from this story is that even after all the warnings of not giving sensitive code you receive on your phone to anybody that calls you and asked for it especially those you haven't been in contact with, I'm surprised people still fall for this trick. You get luck say you realize yourself on time. Me I dun put that 2FA since for my WhatsApp and it's best everyone does it because Whatsapp hacking are becoming very common dis days because hackers dun dey realize say na Whatsapp many businesses are been dun dis day and that's the easiest way to get contact of potential victims to defraud.
To add to this, I'll just give out a friendly advice to make the security of all our device very strong. Some platforms has the security features of not been able to login from a device or IP that hasn't access the platform with that your account, enable them to make your account strong and this advice isn't just for social media but for every platform that you use and it's important that you exchanges, wallet etc make sure you have an addition security that isn't just your password that'll be needed whenever you want to login, make a transaction or trade. Your bank apps, trading apps etc should all be extremely secured because scammers and hackers are everywhere looking for the next victim to defraud, no go talk say na lack of information cause am because now we dun dey pass the information to be alert and keep your accounts secured.