system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If I put an X amount of money on an account with an interest rate superior to 0, and given an infinite amount of time, am I wrong in thinking that after a long enough amount of time, all money in the world will be in the account?

Let's say I open a bank account and I place 10$ in it. If I have an interest rate of (imaginary) 10%, that means that every month or year, the bank will give me money. Every month, the amount of money on which the interests are calculated gets bigger, thus making they pay me more money. Now, if I wait long enough, is it possible that at some point in time I will have all the money in the world on my account?
gpt
You are wrong. The amount of money in the world actually increases over time. There are more dollars in America now than there were 50 years ago, there's more yen in Japan, and so on and so forth. Your interest rate would need to be through the roof, far outpacing the rate of inflation for this to even be a mathematical possibility.

We'll ignore this for the moment though, and pretend that the amount of money in the world is static. You still would never get all the money, because at some point, you'd bankrupt the bank. The reason they give you interest on your deposit is because they use the money to conduct their own business. You're basically giving the bank a loan. However, if your account got so large that it was big enough to actually have a dent in the global economy, the interest payments that the bank would have to make would be so large that they couldn't do it.

Finally, even if you got around that, it wouldn't make a difference because the world would just start using something else as currency. Money only works when lots of people have it. Once all of the money in the world disappeared into your bank account, people would be forced to use something else in order to keep buying and selling goods. Once this happens, your money would basically be worthless anyone, and probably wouldn't even count as money any more.