You're defining 'harm' in a very literal fashion. I'm arguing regardless that no one was injured or, from what we can tell, fired or anything, they still caused a lot of inconvenience for some people. Yeah, the hack is kind of funny, and it is likely pretty much everyone remembers it fondly[0], and none of this is really a huge deal in the end, but what I'm saying is that it is perfectly understandable to be embarrassed by having behaved this way in the past, I believe it is a sign of maturity.

[0] However, it is not unknown for soldiers, even one's with PTSD, to have an overall fond recollection of their time in the war either, so it's not clear that means anything.