Why wouldn't I?
Yes, I've been doing it for over 20 years now, and used chat rooms before then so I'm used to it.
Although going off some of the replies here I think working in retail before then also helps. It seems relatively easy to ignore absurd conjecture about what I "really" mean or what my secret motive is (or out-right insults for not giving someone the answer they wanted to hear) when I'm not required to stand there and listen to them yelling at my face or required to respond if I don't want to.
Once you've had adults with kids and presumably a job and other responsibilities who should be able to, well, act like an adult screaming at you for being a terrible person because you "refused" to sell them Mario Kart on the Xbox you quickly learn that other people's reactions are not your responsibility.
The weird part is I do mean adults plural, and I'm not generalising, that specific example came up multiple times and people really did get quite angry about it. There were other 'asks' for non-existent games, non-existent hardware, illegal hardware, non-existent sales...it was an interesting job.
To be fair they weren't all bad. One of my favourites was the boys who came in not long after the Playstation 3 was released and asked if they could pre-order a Playstation 4. They knew it wasn't even rumoured to be in production at that point but made the quite reasonable assumption that there would one day be one and wanted to be able to say they were the first in the world to pre-order it. Sadly we couldn't do pre-orders for stuff that wasn't in the database, but we sent them to a store that did pre-orders on paper and I hope they let them do it.