A scenario is most valuable when it can disappoint you safely before real life has to.
If you lower costs without a reason, use income that is not yet agreed or assume an investment return because the decision needs it, you are no longer testing the possibility fairly.
Keep hope and honesty together
Build the hopeful version, then build a cautious one. Ask what evidence would move the cautious figure.
The aim is not to make the numbers say yes. It is to understand what would need to become true, what you can influence and what risk you would be carrying.