That all depends on what we're using to fly. If your plan involves gluing me to a chair covered in helium balloons, then I'll quit. If your plan involves building something repairable and mechanical, then I trust my own abilities to make it as sturdy as you'll need it to be for when you make your test flight.

After all, if the designer isn't confident enough with his own design to give it a first go, then how can a mere assistant mechanic hope to feel safe?