The primary "catch" lies in the rigid risk constraints. Platforms protect their capital by enforcing maximum daily drawdown limits, overall trailing drawdowns, position sizing restrictions, and prohibition of high-risk behaviors like news trading or martingale strategies. Breaching a single rule usually results in immediate account revocation. Additionally, you must beware of illegitimate platforms with hidden fee structures or unrealistic challenge rules. I recommend reading this article which covers the mechanisms, rules, and potential pitfalls of trading with platform capital: https://cryptwerk.com/post/can-you-trade-with-a-platforms-money/.