With those games excluded, SonixLegend's collection actually encompasses the vast majority of the 45,000 or so "full profile" paid games tracked by SteamDB. But with thousands of new games being released on Steam every year, it might not be long until a badge for 50,000 owned games becomes a real possibility.
So what’s good?
It's hard to gauge just how much of SonixLegend's massive Steam collection officially counts as a "backlog" since their private account doesn't offer a public breakdown of playtime for most individual titles. That said, there are only 261 games for which SonixLegend has earned at least one achievement and only 16 that were good enough to merit a user review (they all ended up as "Recommended").
The implications of SonixLegend trying to actually work through their Steam backlog can be more than a little intimidating, though. HowLongToBeat data suggests that finishing just the "top 2,500" games in SonixLegend's Steam collection would take over 2,463 days, or nearly seven years of 24/7 gameplay.
Ironically, SonixLegend's favorite game isn't even one that counts toward their record-setting badge. The user's Steam profile page lists 551 hours spent playing Valve's 2010 free-to-play overhead shooter Alien Swarm. In a way, it's nice to know that, even with access to nearly every paid modern PC game in existence, the one game this user keeps coming back to is a 15-year-old title that doesn't cost a penny.