Trustless is an adjective:
1 Having no trust or confidence; unbelieving; distrustful.
2 Not to be trusted or relied on; unfaithful, unreliable, treacherous, untrustworthy.
Which would likely lead some into a confusion.
You might wonder that SAFE requires no trust but that's not the inverse of requiring trust.
Trustless is like a negative and the reality of SAFE and other distributed systems is they require zero.. trustzero isn't a word but if it was
As for the how.. well you control your data; your system fragments and encrypts your data; and uploads into a shared space that is the network. To be sure of your privacy; security; and freedom, requires zero trust because you are the only one that can access it.
If you want to extend this to faith.. then the network requires a bit of faith in the its being stable and that confidence will follow from network size. After a point there is no need for faith and the robust nature of the network will see it defend your data alongside others. Best route to that is to contribute resources to the network and make it stronger for yourself and everyone else.