Trust your gut instinct over spreadsheets. There are too many variables in the real world that you simply can't put into a spreadsheet. Spreadsheets spit out results from your inexact assumptions and give you a false sense of security. In most cases, your heart and gut are still your best guide.
As a young boy growing up in rural India, most of what I knew of the world was what I could see around me. But each night, I would look at the Moon - it was impossibly far away, yet it held a special attraction because it allowed me to dream beyond my village and country, and think about the rest of the world and space.