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.
Billions of people do not have access to water do you think people like that are going to have computers, smartphones and the electricity and internet to run them, if you can access this forum then the truth is that no matter how difficult your situation in your life you are better than hundreds of millions of people, so it is going to take a lot of time before all the economy becomes digital.