Steam broke their own record last weekend. They reached over 9.5 million concurrent users logged in at the same time on May 10th. Was there something major going on? I have no idea. I don’t think so though.
It’s pretty crazy that even after the major fallout over payed mods, that Steam had that many users on at once. The question though is, was this just idle users or people playing games? This information is unknown. However, either way, these numbers are still impressive.