WHO are the Vatican Bank's 17,400
"Customers?"
What we do know is that Vatican Bank, officially titled the Institute for the Works of Religion, manages €5.9bn ($7.3bn, £4.64bn) of assets on behalf of its 17,400 customers. https://www.ibtimes.co.uk/how-rich-vatican-so-wealthy-it-can-stumble-across-millions-euros-just-tucked-away-1478219
"Customers?"
What we do know is that Vatican Bank, officially titled the Institute for the Works of Religion, manages €5.9bn ($7.3bn, £4.64bn) of assets on behalf of its 17,400 customers. https://www.ibtimes.co.uk/how-rich-vatican-so-wealthy-it-can-stumble-across-millions-euros-just-tucked-away-1478219
And it manages €700m of equity which it owns. Another titbit to emerge is that it keeps gold reserves worth over $20m with the US Federal Reserve.
The bank has been caught up in a number of scandals in the past, including the funding of priests caught up in sex abuse allegations and of money laundering for the Mafia and former Nazis.