Just letting you guys know.
Buy and
sell steam accounts at your own risk.
It's not legal to buy accounts. Your account might get suspended.
Buying, Selling, or Trading Accounts
Accounts which have been bought, sold or traded will be suspended. This includes any other accounts in your possession at the time of the sale or trade, regardless of whether those accounts were also sold or not .
https://support.steampowered.com/kb_article.php?ref=5406-WFZC-5519OP see those emboldened words
Additionaly, if this account is not his and has been stolen, it may be retrieved, further increasing the chance of losing the account.
Proving you own a Steam account is hard. And retrieving it if you have payment details is easy.