As a bearer of a dragon soul, Dante's actions will, whether willingly or unwillingly, be influenced by a dragon's nature.
And now, seeing as Dante had two Dragon souls, this influence on Dante could only be twice as lethal.
And one such influence Dante gained was an obsession with treasure.
You see, for dragons, the pleasure gained from having large amounts of wealth was unimaginable.
For a better choice of words, it was almost drug-like!
And it was this drug like feeling that caused a dragon's obsession over treasure to be strong that it was practically engrained in their very souls!
Even the strongest of Dragons would succumb to their desires when faced with intoxicating pleasure that treasures would give them.
Much less Dante, who only currently held a fraction of the power that the strongest Dragons could have.
Faced with the temptation of treasures, Dante couldn't even resist, or more correctly he didn't even want to!