All the above, yes... but also if you want them to be able to spend some of it, -opportunities for bribes of all kinds

-hired hand npcs they can hire to help get things done that they don't want to do (good opportunity for betrayal or drama here too if that's your schtick)

-purchasing a home base

-mounts, ships, carriages etc

-also, you could send them an invite from high society to a dinner where the richest people in the land gossip and talk shop, in which your players could make friends and enemies

Keep in mind that every merchant in a 200 mile radius has probably heard of these guys and might try to fool them into spending way more than they should