What would happen if someone stole $0.10 from every bank account in the world, but later paid it back using their invested billions?

With roughly 7 Billion people in the world and 2 Billion being unbanked. You have essentially 5 Billion Bank Accounts to steal from.

5 Billion x 10 cents = $500 Million.

Now sure how much you will make from your invested $500 Million. It is not the invested billions you had thought of. Even if you assume that there are twice as many bank accounts as their are people, then you’re looking at US$ 1.4 Billion.

How and where will you invest that, to pay back later on? Unless you’re extremely good at making money, which you most likely are not, since you had to resort to the thought of stealing money from other bank accounts in the first place, your promise to deliver would be a broken one.