It really depends on your use case. Most of my simple chat messages are the same as I would have in any public space. I have no need for encryption, I have need for convenience in that regard. With Telegram I have my chat history on all devices and don’t need to use my phone to connect which are two must-haves for me. For my use case, Signal is the worse option. That doesn’t make Signal bad, just not suitable for me.
As a privacy-concious person I am very much aware of the non-secure nature of my chats, but since that is not a factor of consideration to me when it comes to casual chats with a few friends and family members. The worst thing Telegram could do is analyse my chats and … then what?