If you're going to be that puerile then... I had to scroll past their list of available clients and their recent news section to get to this "Why Telegram" section that first mentions the word "private". So clearly, that far down the page, its not a priority.

Back in reality: The word "private" can mean anything. Every app and website that uses https claims to have privacy and security. If you bother to read their FAQ (which is always at the top of the page and, according to your logic, must be very important), there is a detailed explanation of exactly what is and isn't encrypted.

https://telegram.org/faq#security

I can already hear you typing, "but the average person doesn't read FAQs!" Well, the average person doesn't know or care about e2ee either. And the average person doesn't think Telegram is any more or less private than Facebook Messenger, WhatsApp, Twitter DMs, SMS, or email. The average person just doesn't think about privacy in this way.