What is the question of cash security in such large projects as WebMoney, Qiwi, etc.?

Question

Information Security

Is all data on the amount of available funds stored on the server or on users' devices?

Answer 1

Of course on the servers. It’s generally impossible to store data about money on devices) Well, if someone else’s computer is hacked, and if not, the dude will hack the program himself and add a couple of zeros to the amount?)