Comment by parable

You might be interested in reading the court case against Eric Meiggs and Declan Harrington, which includes charges against the two involving extortion and SIM swapping for usernames. See page 10: https://storage.courtlistener.com/recap/gov.uscourts.mad.215...

While it isn't directly "stealing", the government has brought charges against people in the past for username-related crimes. There are several similar cases, but this is the first one that came to mind.