Microsoft got mugged off here for sure , they cant be worth what they spent
You are crazy. They're worth well more than what Microsoft paid, same goes for Bethesda. Activision's true value is in the $80-$110 billion range.
If the range of IP they got across Blizzard and Acti you don't feel are big, there are all the studios, the manpower, the talent, the technology such as game engines, lighting, effects, animation, tools, cinematics teams, anything and everything they have in there is now Microsoft and Xbox's own.
But if that doesn't mean anything to you, consider that the purchase includes a money making machine in King aka Candy Crush.
Check out their latest quarterly report. No, that isn't a typo, Candy Crush generated more revenue and also brought in more income than Activision and Blizzard Entertainment. More revenue than each, more profit than each.
This is from July 2021 to the end of September 2021. And the potential of turbo charging the popularity of World of Warcraft with an Xbox console launch, along with upcoming games like Diablo IV (PC, PS4, XB1), Overwatch 2 (PC, PS4, XB1)