What if one wrong assumption in my model breaks everything?

You check the numbers again. Not because they're wrong, but because a committee will use them to spend real money, and if you missed something, it feels like your fault. That's the story you've been telling yourself. Here is what's actually happened: you've placed the weight of every decision the company makes onto your own shoulders, then wondered why you can't sleep. The model is yours. The decision is not. You built a tool. Other people chose to trust it, use it, act on it — with their own judgment, their own authority, their own name on the outcome. The anxiety isn't telling you to work harder or check one more cell. It's telling you that you've quietly accepted a job nobody assigned you: guardian of every result downstream of your work. That job isn't yours. Give it back.