UPDATE!
TL:DR - I think I talked him out of buying this 80 Acres by convincing him to purchase the 320 Acres directly next to the current farm when my Aunt wants to sell or passes away.
Talked to my dad tonight about it and while I still think its a terrible idea its not as bad as I originally thought. He currently makes around 7k per year leasing the land he already owns (although it was lower this year due to some insurance deductibles) that he would use to pay off the TWENTY
year loan. This brings the yearly payments down to a more managable 2-3 thousand per year ($12,000 yearly payment - $2400 estimated income - $7000 current income from land already owned)
He claimed to have 3 Aces up his sleeve
1. Wind Turbines - Last year he signed a lease with an energy company for the right to put up wind turbines. Currently gets maybe $1,000 a year but if they actually build some turbines it could be closer to 8-10k.
2. Breakout 200 Acres of Pasture into Cropland to bring in additional income. The current farm has around 400 acres of pastureland and around 200 acres of that could be turned into dry cropland. My uncle is currently in year 3 of a 5 year lease on the land and runs cattle on the pasture so its nothing that would happen soon. This has been his #1 plan ever since he inherited the farm. I always counter with "If its such a good idea why hasn't it been done in the past 100 years" but looking at the farm on google maps its literally the only large chunk of pasture land within 5 miles so maybe it can work.
3. Flip the land and sell it for $2000 an acre. He claims that he could currently sell it to someone right now for $2000 per acre but that my uncle wont sell it to this guy because he hates him for some reason. "This 80 Acres is part of the best quarter in that section, when grandpa passed away someone offered to buy it the next week". He would never actually do this though because as Steve Dave pointed out earlier farmers only like buying land.
My advice was to not count on any additional money from the Wind Turbines until they actually start construction. If they do build the Turbines save the money and if he still wants to buy more land when my Aunt sells or passes away (She is 6 years older and does not inject snake venom) then he will have a down payment and more farm revenue coming in to purchase her 320 acres that are contiguous with the current farm.
Long story short I have no idea how anyone makes any money farming.