why is there a max amount of money??

What do you mean??

I'm 99% sure there isn't a money cap, of course, I could be mistaken.

It's $2,147,483,647 in the bank and $2,147,483,647 in your pocket

I think its the max an int type can hold

That's interesting, I never knew that. I guess it makes sense why you can't sell certain high level pokemon, because their worth exceeds the max money.

But 2,147,483,647?
That's one less than 2^31. I only know this because I have memorized, 2^32, which is required by... Let's say a particular class. So yeah, it sounds like a binary coding--programming situation. One that'd be extremely difficult to change.

But if you want to be rich, offer $1 million for coins (that's the average sale price for coins, correct?) and start accumulating them. $Billions can just be your cents... What an inflation.