I am a bit surprised to hear telegram was not end-to-end encryption.  
I have been using it as plp around me wanted to use it.  They say it is safer. 

But even if the messages were encrypted, most of the devices are not. 

Privacy has become a very difficult thing almost like an illusion.  

I do think on-line conversations are like talking loud on the heavy traffic place. Whatever I say in public will be public and could be overheard. 

The important thing is the privacy of thoughts. Whatever in my head is private and I am free there.