"Much higher (100x) for a strategic acquisition from a company like Microsoft" is grossly exaggerated. There were only 171 companies worth more than $88.3bn (<100x a billion) as of December [1], a number that may have even dropped during current market conditions. Activision Blizzard is worth today ~$60bn and Microsoft is buying it at ~$68bn [2]. It's one the largest acquisitions they've made, and the largest publicly known amount by far [3] with LinkedIn (2016) second at $26bn.

Agree that Valve is likely worth at least 10x a billion, though.

[1]: https://asia.nikkei.com/Business/Markets/A-tale-of-2-markets... [2]: https://news.microsoft.com/2022/01/18/microsoft-to-acquire-a... [3]: https://en.wikipedia.org/wiki/List_of_mergers_and_acquisitio...