However, due to the conversation rate the platform gives, cashing out that many Robux would net creators a total of $350. Over the past three years, Roblox's developer exchange fees have ranged ...

Roblox buys back the Robux at a set exchange rate (currently at $0.0035 per Robux), and records those payments as "developer exchange fees".

That's why Roblox users also use YouTube to stream and promote their games. Roblox's revenue rose 56% to $508.4 million in 2019, then grew another 82% to $932.9 million in 2020.