OK, I think I see the disconnect. Your Excel spreadsheet isn't telling you NetWorth, and you aren't using Net Worth to make a decision. Your Excel spreadsheet is tracking your costs/expenses on old equipment, and, somehow you use them for making decisions on new pieces of equipment.
Much different than a NetWorth decision.
Again, his numbers are completely independent of your Net Worth, and your Net Worth has no impact on his numbers. The neighbor down the road who is dang near broke would also see similar numbers from the John Deere dealer with respect to fuel burn, production, tax benefit, income, etc, just as the Mega-Corporation Conglomerate Farm located just over the hill from you.
The John Deere numbers are completely independent of Net Worth.
Hopefully you buy new pieces of equipment based on the future positive revenue stream (NPV, or Internal Rate of Return) and not based upon Net Worth.
I have known lots of farmers who had high Net Worth and were able to farm until they ran out of Net Worth.