Some level of practice is necessary and few will succeed if they walk into trading blind.
You mention that everyone needs a plan. Testing that plan in production can wipe a trader out before they ever really get started. Testing your plan, your strategy, your algo, in simulation is critical to validating your idea and validating that execution of your plan will indeed be profitable. It’s true simulation is not the mirror image of production level trading and lacking “skin in the game” while trading in simulation alters your psyche, but if you have a plan, and stick to your plan, there is no need to worry about emotions. Trading should be a boring, non-emotional process. It’s best to learn this control and make your emotional and trade logic mistakes in simulation.