I did mention it sounded ludicrous... when you consider the success of the playstation brand before hand though i feel like a company that well versed in gaming in general should have a decent knowledge of how to make a popular PC launcher. Valve wasn't a very old company when they first made steam and it took them decades until they first broke 100 million MAU. Sony is established and has a gigantic name brand. That combined with the growth of PC gaming in many areas would probably lead to many previous Playstation fans trying PC for the first time to flock to their launcher. At least, thats my hypothesis
When you launch a product you have to determine what kind of profit model you're looking at.
Would Sony need to amass a large enough userbase QUICKLY, yes and no.
They need a large enough userbase to warrant any cost in getting publishers to put games on their launcher. Otherwise they would be just like EA, Activision, or Ubi-Soft.
That being said, they don't need EVERY title to come out on their launcher in year 1, but ideally for the Publishers if they can sell games for ANY better margin on the PS Store on PC, they'd do it. So if it's 25% compared to 30% on Steam for a large title and I think the game could sell 5 million copies, I'd rather they sell on PS Store on PC than Steam.
70 dollars a pop for 5 million copies is 350 million dollars. At 25%, you're looking at 262.5 million and at 30% you're looking at 245 million.
17.5 million is no small number for the same game, with MAYBE a requirement of programming sync saves and trophies, that you already programmed for on the PS4/5 version.
Sony also makes a number of deals. So does Sony make a deal with TakeTwo to have GTA6 be exclusive on PS5 and PC (via PS Store). Expensive deal for sure, but maybe one they'd do in the face of Call of Duty. That their deals could be extended to PC, make the deals much more enticing. Deals like FF16 that end up coming to PC, would almost certainly be exclusive to PC via PS Store, with the same sort of time exclusivity.
But that is where the margins come into play, but where Sony has a huge advantage over Steam. That's where Sony needs to be careful is not overextending themselves with deals that aren't working in terms of generating more active users, but they also have PS+ that they could extend to PC users if they brought PS1-3 emulation on PC.