Of course it can't. Bitcoin is not accessible to all people specially the people who live on below poverty line. Value wise it is the most expensive currency but imagine going to the store buying things using bitcoin and waiting for a transaction to be confirmed. Hell no.
Bitcoin is accessible to all people. Because now a days uneducated person also aware about bitcoin and they are going to invest into bitcoin because they know that their future is secure in bitcoin so that's why it will replace fiat. Bitcoin having potential to replace fiat. While your statement about poor people are somehow right but now they are also become a familiar with bitcoin. Because bitcoin has marked a record around the world. Bitcoin has promised people that it can reduce poverty. So as you are talking about poverty line. Then after 2 to 3 years there will be no poverty line because they will become a part of bitcoin like us.