correct
and one may do so by verifying its underlying code, as it is all open-source

if you are unable to verify by yourself then yes, you'd have to trust someone. but that someone can be one who you already trust, eliminating the need to rely on people you don't trust (which is the current state of affairs) 

 This all day.

You can verify and trust the code. But most cannot and will not be able to.

They will have to trust someone else.

And also agreed. Once in the system, you don't have to trust others to hold, or spend.