I don't know why money being digital would make it any worse for the poorer people. As long as they have inclusion in the system, the amount of money you have doesn't matter.
It will be not secure for any poor because it needs an internet connection for its operation which the poor doesn't have
That is beginning to change, most people now have a cell phone and an internet connection nowadays.
I think that is what the OP is pointing out, the possibility of the less favoured not being able to be included in the system and become even less "favoured" by the system.