3465 € in 21 years at today’s prices for 287 games. Given that I mostly buy at historical lows the estimate of 1033 € that can be found on the same SteamDB page applies to me.

3,6 € per game, 49 € per year.

Given the tears, the emotions and the joy I got repeatedly from all those (mostly indie) titles, it’s well worth it. Praised be GabeN and all of Valve!