Theft is easy
But finding merchants that can launder them for you can be a bit harder, especially now everything is electronic.
One of the reasons why credit card companies charge merchant such hefty fees is that they serve as vetters of customers. They have, and do use, considerable resources to track down and punish abuse of their payment processing cartel. Anyone laundering cards faces the risk of paying for any products paid for with them, plus any criminal charges and possible loss of banking access.
The industry talks up the sums involved when it wants more power, higher rates or protection from competition but in reality even in the fraudsters' paradise of America the costs are not that high. They are other, safer ways of defrauding people. Just as Goldman Sachs, JP Morgan, et al.!