This is possible under perfect conditions. Black walnut can be ready to harvest in 30 years with a 30-inch-diameter log (again, under the best conditions). Also you can sell walnuts from the tree about 3-4 years after planting. The tree can grow up to 3-5 inches. 100,000 trees per acre in a year so yes, you can make a lot of money with just a few trees in your yard. Selling will be a nice bonus plus you'll enjoy all the years your yard produces walnuts.

I remember watching a documentary a long time ago about some royal family in England and their estate had been in the family for over 100 years. He said that it has been over the years that it is his duty to plant trees not for himself but for his future children, grandchildren, great grandchildren etc. Their property was beautiful! Beautiful big trees everywhere. I think we don't do that here in Kashmir. Perhaps one reason is that we are so mobile these days. Breeds do not tend to stay on only one property. However, if we stopped thinking "I won't be moving to this property in a few years, why bother planting and caring for trees", and we would all just plant trees, then when you move in The new property will already have beautiful trees!