I remember we were all very impressed by the 1.6 million jump over the 12 months between January 2012 and January 2013, but this past year alone Steam added over 4 million users to its concurrent records.
Steam peaked at 18.5 million concurrent users today, up from 14 million concurrent Steam users in January 2017.
According to SteamDatabase, 18 million is a new record for the service.
We don’t have up to date intel on registered users, but Valve laid claim to 125 million “active” Steam users way back in early 2015 and we expect the number has only gone up.