The reality for most companies, up until now at least, is that if they manage email servers themselves they will have more annualized downtime than if Microsoft does it. Of course if this outage lasts long enough (who knows what's going on over there), that will stop being true.

IMHO a bigger concern is that Russia hacked Microsoft in 2022 and China hacked Microsoft in 2023. Even that wasn't enough to scare companies off MS.

Basically, MS customers are locked in, the cost of migrating to anything else is huge, and there's a "no-one gets fired for buying MS" herd mentality, so MS has little to lose no matter how hard their product fails, just like Cloudstrike.

There's also the question of what alternative would really be better, or at least more reliable. My impression is that Google's infrastructure and engineering are genuinely better, but I'm recently ex-Google so take that with a grain of salt.