NeokratosRed intentionally went with a low estimate in order to get a minimum figure for how much money Harry has.
Since we know that one galleon equals about $25 (American), and that all the gold coins are galleons (sickles are silver and knuts are bronze), we can determine that the minimum value of the money in Harry's vault is...
Holy Hufflepuffs! Harry was REALLY rich.
Of course, that's only Harry's assets, and a conservative estimate at that. So really, his net worth could be MUCH more than that.
A bit of clarity on the assumptions made here: * This does not take into account other properties, like Grimmauld's Place * This is not canon, what I meant this is as close as canon as we can get, since although the books are our official reference the movies come as close second, since in a way or another J.K. was involved as a consultant, and it's the second-best material we can work with in some aspects. (The first being J.K. herself) * This was a minimum estimate, which means that I took all the precautions of the case to underestimate the actual wealth. In the book we can read: Harry gasped. Inside were mounds of gold coins. Columns of silver. Heaps of little bronze Knuts.
[This means that there were multiple mounds of gold coins, not just one, and there was also silver].
If we take into account the actual width and depth of a Vault we can see the value skyrocket to tens of millions, assuming the whole floor is covered in gold and silver, so I just tried to keep things as low as possible.
So with Harry's net worth possibly being near the tens of millions, it's clear who was hosting the Battle of Hogwarts victory party.
