CDPR has a market cap of 4.63 billion. 7 billion is a bit extreme even with a premium. I think we're talking closer to 6 billion.
Both the Witcher 3 and Cyberpunk are absolutely massive games. If you compare them to Naughty Dog who is the current Sony crown jewel with maybe the exception of Bungie who I'm discounting because they are going to self-publish, CDPR would immediately become your biggest studio and you would immediately get 2 massive franchises to add to the PlayStation suite, and a genre that Sony isn't strong in. Witcher 3 sold 30 million copies and Cyberpunk has already sold 13.7 million copies. 43.7 million copies from one studio in essentially the span of a generation? That's significant.
As for GOG, you get the existing framework. It's not about the games currently in the store. You rebrand GOG to PlayStation Store and you immediately get an avenue into self-publishing on PC as well as royalties for other publishers on PC. PlayStation Store would be an immediate competitor for Steam and EGS, whereas if they created their own storefront they'd have to create that framework from scratch. Just like with Bungie it fast-forwards a key revenue strategy. Instead of paying Valve money to sell their games on Steam, they can sell their own games through GOG/PSN or some strategy of games releasing on GOG/PSN first and then eventually on Steam. Sony can also put a lot more money into GOG to make it a real competitor, whereas CDPR never had the money to do that.
Also Sony didn't throw them under the bus. They know their game was busted. If anything they threw Sony under the bus. But none of that is personal, it's business. What being owned by Sony allows CDPR is to stabilize their workforce and an influx of resources and collaborations. There is no way that Cyberpunk releases the way it was if it were a Sony first-party title. It would have just been delayed and sony would have eaten the cost. They released the game because they'd already paid for an expensive ad campaign and that in conjunction with the cost of developing the game for another year was too much for the heads of the studio, so they said F it and they released it. Those pressures don't really exist as a first-party studio, at least not to the same extent.
You look at the success stories of Sony 1st party studios and it shows the growth potential of any quality studio. Even Fumito Ueda was given every opportunity with Last Guardian.