What if you record, as text, everything you say? Would that be convenient, or dangerous?

With free software, if you choose to record your vocal utterances in your computer, you will be able to keep your transcript encrypted so that you control when and how it is used.

But if you use someone else's server to convert the text to speech, which is an example of SaaSS (service as a software substitute), that someone else will have your transcript from the get-go.