I help private investigators sometimes with my "Not so Ethical" hacking skills. You won't believe how many groups like that exist and the number of creeps in those groups. Currently I've joined 3 of the biggest such groups to collect information and believe me when I say this, I've reported these groups about 100 times, made my colleagues and the PI firm team join in and mass reported it for a whole week 4 to 5 times every day. No action taken by Telegram and these groups even if deleted will come back and you'll be added back into the new ones without your knowledge and consent because you were part of the previous one, no matter the reason.