My money is already safe in the bank (blockchain), and satoshi's coins are as safe as everyone else, why would I who knows my coins are safe pay 10% and the guy who has just moved coins 6 months ago not pay since we both are offered the same security?
50 satoshi or 100000 Bitcoins we;re both offered the same, the blockchain doesn't care about the amounts!
The blockchain is only as safe as how many miners are on the network. If miners end up only getting 50k per a block some day then it would only require 50k worth of power to create a false block. That 2.6 Billion USD worth of power to basically shut down the network for a year.
This is a lot of money but if bitcoin is to become a global reserve currency 2.6 Billion is a small price to pay to disrupt it.