The uneven distribution of wealth causes problems for several characters. Bassanio seems to be a noble person, but he suffers from a lack of money, forcing him to selfishly borrow from Antonio, while the vengeful Shy lock makes substantial profits by exploiting others.
Moreover, wealth is presented as fickle (changeable) and liable to disappear at any moment. For example, Antonio is confident that he will have more than enough money to repay his loan, but he ends up losing his fortune. As Tubal informs Shylock: Antonio had a ship of rich lading
wrecked on the narrow seas (3.1)