The reason bankers and the wealthy are throwing mountains of capital and political leverage behind mass adoption of cashless societies is the greater control it offers. If they illegalize cash and paper money. Then they have complete control over monetary transactions.
I think it's also governments who are heading off currency liquidity risks. Everyone is becoming increasingly worried about the next financial crisis and its effects on liquidity. When depositor money is locked inside the banking system (as opposed to cash), it's easier to prevent shocks to the economy. There are no bank runs in a cashless society.