The Trap of Marginal Thinking

Feb 16, 2020 3 min read

Here is an excerpt from the book “How will you measure your life?” by Clayton Christensen on marginal thinking. The reason that I am producing it here is that I have questions regarding it, that I have produced in the end. Please comment  or email me with what you think. Thanks!

… a little upstart called Netflix emerged in the 1990s with a novel idea: rather than make people go to the video store, why don’t we mail DVDs to them? ….. Netflix customers paid a monthly fee - and the company made money when customers didn’t watch the DVDs that they had ordered. As long as the DVDs sat unwatched at customers’ homes, Netflix did not have to pay return postage - or send out the next batch of movies that the customer had already paid the monthly fee to get.

By 2011, Netflix had almost 24 million customers, And Blockbuster? It had declared bankruptcy the year before.


analysis shows that marginal costs are lower, and marginal profits are higher, than the full cost. This doctrine biases companies to leverage what they have put in place to succeed in the past, instead of guiding them to create capabilities they’ll need in the future.

The right way to look at this new market was not to think, “How can we protect our existing business? Instead, Blockbuster should have been thinking: “If we didn’t have an existing business, how could we best build a new one? What would be the best way for us to serve our customers?”

Nucor had succeeded in getting an edge in this market by using lower-cost technology than the traditional makers had for making steel, in new types of plants called “mini-mills.”

As Nucor began to eat into U.S. Steel’s market, a group of engineers at U.S. Steel got together and concluded that if U.S. Steel was going to survive, it had to build the kind of steel mills that Nucor had. That way, it could create steel products at a much lower cost, remaining competitive against Nucor. So the engineers put together a business plan, which showed that U.S. Steel’s profit per ton would increase sixfold in the new plannt.

Everybody agreed this was a promising plan… everybody except the chief financial officer. When he saw that the plan involved spending money to build new mills, he put brakes on. “Why Should we build a new mill? We have 30percent excess capacity in our existing mills. If you were to sell an extra ton of steel, make it in our existing mills. The marginal cost of producing an additional ton in our existing mills is so low that the marginal profit is four times greater than if we build a completely new mini-mill.”

The CFO made the marginal-thinking mistake. He didn’t see that by utilizing the existing plant, they were not changing their fundamental cost of making steel at all. Building a completely new mill would have had an up-front cost, but then given the company a new and important capability for the future.

As Henry Ford once put it. “If you need a machine and don’t buy it, then you will ultimately find that you have paid for it and don’t have it.”

So after this Clayton explains how existing companies want to leverage their existing capcities, brands & not start from scratch in a new kind of disrupting market. And how this is a big mistake. New entrants don’t have an existing cost structure, so they start from a clean slate & this turns out to be their biggest advantage.

Now here are my questions or doubts,

  1. Both Blockbuster &  U.S. Steel, didn’t know if the new entrants are a wave or a fad, so they acted late. What would be the story like if these new entrants failed for different reasons, not related to business model? How would that shape the market?
  2. Wouldn’t the right strategy for Blockbuster be to provide both kind of plans, the existing rental ones & the new subscription ones, and push for where-ever the growth came from? Why couldn’t they do it? Existing structure of franchise model, etc…?
  3. Wouldn’t the right strategy for U.S. Steel be to use up that 30% capacity, sell these goods at the new costing & have all further expansion in the mini mills?

What am I missing here?

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