Let them underestimate you. People don’t guard what they don’t see coming.

Being underestimated is inconvenient and occasionally very useful. Nobody prepares for the person they already dismissed, so you get to work without scrutiny, make your mistakes without an audience, and turn up with something finished instead of something announced. Correcting their opinion early costs you all of that.

Stop arguing about what you are capable of and let the work make the case later. Keep the thing you are building quiet for a while, not for drama, just because it grows better without commentary. Let the finished version be the whole conversation.