I've watched a bit of iracing on Twitch, it seems interesting enough but I don't have the combination of time/cash/facilities to make it worth actually playing
Those guys spend more on their sim rig than most people do on their car.
I haven't had the luck of running into any big names on iracing yet (low irating probably doesn't help), but I know Sainz was on constantly up until the F1 restart. Now Fernando Alonso is on constantly, I guess trying to get track time in for his rumored F1 return.