After the Lorax and the Once-Ler caught up a little bit. They started to discuss where the Once-Ler went wrong, starting with the scarcity of the Truffula trees. Truffula trees were few and far between, only being located in the one specific valley that the Once-Ler found. Since they were limited, they were very valuable. And the demand for them from the production of the Thneed was far greater than the amount of trees living.

However, the Lorax did praise the Once-Ler for being a good businessman. Knowing to produce the Thneed, a thing everybody needs, a product of all uses. Producing them from Truffula trees and knitting them together. And then selling them to the people of Thneedvile.

The Once-Ler was grateful for this admiration and went on to further to explain that he took the 4 factors of production into account. First one being land, the land he spent days searching for and eventually found. And using the resources he found there to start his business. Second being Labor, this was maybe his greatest idea. Hiring his family as his employees was cheap and didn't require much training. Next was Capital, all the money the Once-Ler made at the beginning he spent on better machines to help boost the business. Lastly was Entrepreneurship, once the Thneed became big, the Once-Ler was able to put his face on billboards. Ultimately all of these things worked to perfection and resulted in a booming business. 

The Lorax despite disliking the Once-Lers actions, had to admit he was a good business man. The Lorax then thought back to his decisions when it came to protecting the trees, and how he could have chosen differently. 

While the Lorax was reminiscing on past decisions, the Once-Ler; who spent decades doing this, decided to share his wrong choice in opportunity cost. He explained that instead of copping down all the trees for instant profit, he could have slowly harvested the material required for Thneeds and continued to plant more trees. Creating a sustained longer term business. The Lorax listened, not amused.  

The Once-Ler then talked about how he almost started to make Thneed blankets but would unsure how they would sell. He made a PPC to look over how it would go and decided that point E would have been the best spot of maximize profit. Replanting the trees, as discussed earlier would have boosted the curve to the right, resulting in more profit. Some of the trees dying would hurt the profit and make the curve go inwards.