lmao how the forget do you spend $50 without even realizing it? has roblox's payment system really gotten that different?
He didn't. There's no way to 'accidentally' spend money on Robux, because the only way to purchase it is by purposefully going onto a page, selecting how much you want, and paying from there.
You can't go ingame, have something pop up, and click "buy robux now!" because there is no way for a game to prompt you like that. You'd have to have the robux before you even entered the game.