This is why everyone should be caution when dealing with something related to telegram, especially the newbies. You never know what might be lurking in the shadow.
Yes, Telegram is known as the empire of online scammers, and if we still have someone who trusts a stranger's claim on this forum, then the person is not worth being in the online space.
Scamming activities like this don't happen only on Telegram, so people need to be more careful on every social media platform, not just Telegram, because online thieves use different strategies on different social media platforms.
Assume we consider buying/selling Telegram usernames, there's an official website where this can be done, so it should be understandable that any individual trying to offer a service outside of the official marketplace created by the Telegram team is up to no good.