This sentence is not talking about money in general. It is talking about a specific set: "all the money in the world", as if it was a specific quantity you could receive:
Suppose I gave you a box with all the money in the world. How would you choose to distribute it?
Other examples talking about a specific set of money:
Do you still have the money I gave you for your birthday?
The money donated to charities should be included on your tax forms, if you want to take the deduction.
It is possible to talk about money as a concept, in which case you would not use the definite article. Examples of this:
I don't care too much for Moneymoney won't, and money can't buy happiness.me love -- John Lennon / Paul McCartney
A wise person should have money in their head, but not in their heart. --Jonathan Swift
Money is a terrible master but an excellent servant. --P.T. Barnum
It is possible to say "all money in the world" to reference the global concept of money, rather than a specific quantity.
All money in the world, in whatever form, relies on the collective agreement that it is worth something. Even a brick of gold has no value to a starving man, unless he can exchange it for food.
[Edit] With regard to FumbleFinger's objection: I would claim "money donated to charities" is either a kind of ellipsis, or else refers to a conceptual subset of the concept of money. In my example, it makes little difference whether I'm talking in general about the practice of donating money, or of a specific instance of some quantity donated. The second half of the sentence applies either way.
Conceptual example: Money (which has been generally) donated to charities should be declared.
Ellipsis example: (The specific quantity of) Money (which you have) donated to charities should be declared.
I think a more in-depth exploration is out of the scope of the question, as OP asks only what the definite article means in this context, and not whether the definite article is required.