Bullshit.

If you want protect yourself for random network administrator on your network line, of course.

Telegram and Signal both use TLS. They are identically secure from transport-level attacks.

If you want protect from anyone (government for example), of course not.

Of course yes. If you want a more private group chat, or an actually useful 1-on-1 encrypted chat that works across multiple devices, Signal is the only option (out of the two, there are way better alternatives like XMPP and Matrix). For 1 device-on-1 device E2E chats, Signal and Telegram are about the same level of security, except Telegram’s protocol sees less scrutiny from the crypto community.

As telegram. If you think that some drug dealers create public chats with sell drugs, so… you are wrong. All work with darknet. In telegram all of them use only private one-by-one crypto chats.

LOL. I see drug ads on the street all the time. The one time I checked, it pointed to a publicly available Telegram bot.