People who signed up on Telegram were set up to fail right from the get go. It doesn't feature default E2EE, it's not private, it's not secure... but there were plenty of users on there looking to buy whatever dark net goods and services you can offer. It's completely stupid when there are much better alternatives out there, but people go wherever other people are, just moving as a herd instead of a lone wolf. With everything that has happened over the last years, including the arrest of the Tornado Cash and Samourai Wallet devs, it's clear that it's no longer possible to resist the government in any way out in the open anymore.