Be wary if you are added without your consent to a group, its one of the signs that a group is a scam, legit projects will not add without asking for your approval first, I have been added so many times in groups and these are mostly related to ICO, trading, and airdrops you can hit report spam and leave once they added you, don't communicate with these people they are good with words to compel you to invest.
Why don't you disable that option to be invited in other groups without your consent in Telegram settings and change it to your contacts only?
I literally waste as much time on telephone scammers as I do with such things on Telegram myself, good points raised as well ofc...
I used to do that as well, thinking that I am saving someone by wasting scammer time, but the amount of scam messages I receive on Telegram is so big that eventually I stopped. I may still play that game if I see an interesting approach, but in 99% of the time I just use block&ignore. The big difference between phone scammer and Telegram scammer is that latter can chat with many people at the same time (and they probably do) so its questionable how effective that stalling technique actually is.