Question

__ all his wealth he is unhappy

Answer 1

For

Step-by-step explanation:

Using

At all his wealth he is unhappy (At represents a place so doesnt match)

Of all his wealth he is unhappy (This sounds like your using it during an explanation, when the statement wants to conclude something)

or

On all his wealth he is unhappy ( This sounds like your putting a bet)

Hope this helped :>