Wario is an entrepreneur. While working at his businesses he is a formal and smart. While he has a bad temper, he is often able to keep it in check. The brash and cocky personality he has is one he only puts on when around his friends, such as the Mario Bros. and Waluigi. While he was a treasure hunter in his past, he now has no need for it, as he used the money he gained from it to fund his more profitable business ventures. How many? Well he has:
-A Gold Mine
-A Scrapyard for ships
-A Dam and a Ski Resort
While still having enough spare money to buy an entire colosseum.
Essentially Wario is the embodiment of the American Dream.
Related to this, there was an incident in the Mushroom Kingdom's past where many people bought ships , but then the Kingdom had an overabundance of them, making them almost worthless, while making scrapyard dedicated entirely to getting rid of ships highly profitable. This explains why Wario would own one of these.