This is the problem when you joined a group that is composed of cryptocurrency enthusiasts. More likely they will add you on another group that they created without you knowing. Just like what OP said, just hit spam and leave the group. Is there a settings in telegram that does not allow anyone to add you in a group with out your permission? Sometimes its really annoying to see that you are added to a new group that you did not join.
For telegram users, if you want to avoid such a hassle of being added on random groups:
1. Open telegram app
2. Go to Settings
3. Click Privacy and Security
4. Under Privacy, click Groups
5. Select My Contacts, instead of Everybody
6. (optional) Under Add Exceptions, you can add users on Never allow too
Explore the Privacy and Security page to see what else you can do (ex. Manage your Blocked users, Who can call you, etc).
Wow I had Been using telegram for long time now but never had a chance that I explore this and by surprise?here now there are plenty of action I can do just to protect from being added without permission or being spammed by private message from random scammers
Thank you for this now I am exploring my apps lol 😂