Close to 40 years ago, I was reading an article that covered the profits that could be realized by planting a 10 acre plot of Juglans Regia trees and harvesting, if memory serves, after about 50 years.
I was in AK at the time and mentioned this to my dad who has plenty of land here in ID. His response was "hell I'll be dead before they can be harvested and who's going to take care of them." He never did plant the 10 acres but it evidently piqued his interest, because he ended up planting about 5-6 trees, which are now getting fairly large and producing an excellent nut crop every year.