Money - Countable or Uncountable noun

This page suggests that we use much with only uncountable nouns whereas the use of many/several is limited to countable nouns only. So I conclude that money is uncountable noun as I've heard people saying phrases like

So much money!

But, We do count the money in our daily life then why is it that money is considered an uncountable noun instead of countable? What if I say

I have $500 to spend

Wouldn't the money be considered countable in this case?

Edit The question may be considered duplicate of the suggested question but, in my opinion, the question on that link itself is not answered properly.

Answer

Sugar is uncountable: grains of sugar are countable.

Air is uncountable: oxygen molecules are countable.

Money is uncountable: dollars are countable.

Sometimes we want to use a collective term for stuff that you use to buy things with- that's money. When you want to start quantifying (counting) it, you have to use a currency- dollars, dinars, yen, euros.