Also keep in mind a few games, such as iRacing, run off their own client. But even then, iRacing boasts of 70,000 members.
Good point with iRacing. How many people do you know, who have a wheel and what’s the percentage of them having played iRacing in the last 3 years?
Personally, most of the people I know somewhat personally online that have a wheel – most of them have some serious equipment, Direct Drive and PT1/Heusinkveld pedal owners, meaning they’re pretty well off, they have the money for iRacing – and not more than 50 to 60% have played iRacing lately. I wouldn’t believe the number is higher than 30% of wheel owners that have played iRacing in the last 3 years. Also, out of all iRacing sim racers I know, nobody plays ONLY iRacing and wouldn’t have connected their wheel to play a game on Steam.
If 95% of those 70,000 iRacing subscribers have a wheel and not more than 30% of wheel owners have played iRacing in the last 3 years, that would add up to about 220,000 wheel owners. I know, a lot of bad estimates, but anything oder 200,000 sounds really low to me.
About music instruments: Guitar Hero and Rock Band were huuuge for a while. The first Guitar Hero sold over 10 million copies and, checking this on Wikipedia, in 2008 the biggest gaming franchises were Mario, Guitar Hero and Rock Band (holy shit!). The entry price for the hardware is almost nonexistent these days as you can’t even give those instruments away to charity, they have too many of those already. What is surprising is that people connected them in 2015-2018 to a PC with Steam running, since the newest versions are on console only (Rockband lost their Fig crowdfunding campaign for a new Rock Band on PC in 2016). Maybe a lot of those instruments in the survey are real guitars to be played with Rocksmith?? *shrugs*
Checking Steam Spy: Their estimate for Rocksmith 2014 owners on Steam is 500,000 to 1,000,000.