They are not the one responsible for that, they were able to organise the pump and dump , just that maybe you bought it at the wrong time and the market dumps on you. Sometimes when there is a huge selling pressure it will be very difficult for you to sell your cryptocurrency on binance. But In all the same we should try as much as possible to avoid telegram for any crypto activities.I have actually fallen a victim to a fake telegram group that is a pump-and-dump group. I thought it was a real group because it had about 30,000 followers in the channel. When they started the pump and dump I bought the coin and was not able to sale. Since that day, I have become wiser.