In every video game, utilizing game mechanics to your advantage beyond their scope is called exploiting and that's what you did. You discovered a flaw in their code/logic and exploited it to your advantage.

Would you have stopped if they hadn't shut down the site? Or would you have drained the whole bank?

There are hard-working people behind @epicdice and what you're doing is sh*tting on their business, because you've outsmarted them.

Take a dive into yourself and think about how you'd feel if you were in their shoes. Would you prefer that someone would tell you about bugs or would you prefer to wake up one morning and have lost thousands of dollars and have your business wrecked?