If someone robs a bank, or steals a wallet, they're probably hoping to get as much money as they can. If that wallet happened to $1B in it, I don't think it makes the thief more heinous. If we sentence people based on the amount of money they manage to steal, we're sentencing them largely based on luck.
It's not possible to accidentally steal $1B when your intention was to steal $10K. Scale does matter - this isn't "luck".
But if the wallets each only contain $100 and you steal enough of them to get to $1 billion, that is qualitatively different from stealing a single wallet. The man committed fraud repeatedly and caused financial hardships for tons of people. He wasn't lucky in how much he managed to steal, that was a combination of effort, skill, and reckless disregard for the wellbeing of others.
If you shoot someone and hit their head killing them or just their ear, its a matter of luck (and possibly skill), the charges are different. The justice system judges based on intent as well as outcome (i.e. execution X luck).