Why? Microsoft is a proven bad actor while the startup might have good people of you're lucky.

There is a nonzero chance that said startup gets bought by Microsoft or worse.

Honestly I would have thought that 5 years ago. But given the latest news on what they are doing, and how they treat security, I honestly have lost all faith that they can handle that data with care.

Laundry list of breaches: https://firewalltimes.com/microsoft-data-breach-timeline/

Profit over customer: https://www.propublica.org/article/microsoft-solarwinds-gold...

> I would trust Microsoft with my voice more than some random startup.

I bet you haven't read their privacy policy. It starts with: "Your privacy is very important for us." /s