Historically speaking very large dominate companies don't really last that long. The idea that they offer a lot of stability or job security working for a big company versus a small one doesn't often pan out.

Like if you look at fortune 500 companies from 50 years ago there is a lot less overlap with the 500 companies of today.

The companies that stay at the top the longest tend to be ones with close ties to the government, like defense agencies. And more socialist the economy the the longer they tend to last.

There are a few reasons for that.

One is that 'economy of scale' is a sword that cuts both ways. Maintaining a large organization is expensive and difficult. Companies are naturally risk adverse and they will incorporate "lessons learned" into their bureaucracy, which is effectively the operating system in which the organization operates off of. The larger the organization the more complex and expensive it is to maintain that "operating system".

A easy example to illustrate this is the requirements for "physical security". You don't want random people walking into your business HQ and making off with stuff.

A smaller business with, maybe, 100 or 200 employees... most everybody knows each other at that point.

There is a thing called "Dunbar's number" and it represents how many people a average person can maintain a close personal relationship with and it caps around 150 or so. So in a organization of 200 people pretty much everybody knows everybody. You can do things like have the owner hand out keys to people that need to open up in the morning, cleaning crew, and people that need to shut down at night and more then likely keep that straight in his head or with very simple checkout system.

Compare that to a company with 2000 or 3000 people. At that scale a typical business is always going to be hiring and firing somebody. People and contractors and such things come and go. So if you walk down a hallway during business hours you are going to run into people you never seen before, people you might have said 'hi' to once or may not be sure about, etc.

It is very possible, at that point, for some random guy to get a hold of a company directory somewhere and memorize a few higher-ups names and simply dress the part and they could just walk in and do pretty much whatever they want. People will just assume he is a new hire, working for some other department, visiting from some other branch, part of a cleaning crew, or a contractor.

So at that point you need to probably invest in a security guard or two. You'll need name tags, badges, HR software to keep employment straight, etc etc. This means more contractors, software for the security system, cameras, guy to come in and wire up badges, a person to maintain lists of names, cameras, software directory systems for the computers, etc etc.

Costs go from maybe a couple thousand a year to now having to maintain entire salaries. Looking at few hundred thousand dollars at least.

And when you get into companies that have many multiple thousands or ten thousand of employees... You have multiple branches, lawyers on staff, HR departments, security departments, IT staff.... Thousand of people employed for the sole purpose of maintaining the organization. None of that contributes to the bottom line from selling goods/services to customers at prices they are willing to pay.

Then you start to run into problems like "Pournelle's Iron Law of Bureaucracy" (look it up). This is where the people that run the bureaucracy tend to be people who are least productive and mostly interested in internal politics.

This has a side effect of "ossification". Large complex organizations tend to extremely slow to change.

This then conflicts with the second major issues...

The economy is always changing.

Large companies can become large and dominate through being innovative and adopting new technology. They figure how to supply customer's needs cheaper, better, faster, etc.

So in a free market it wouldn't be unusual for various companies to rise to dominate their industry in as little as 20 years.

But time changes things and markets are (mathmatically) impossible to predict. Which means they are effectively random. Also competition means that other competing companies will adopt those changes and start introducing their own.

So something that made a company very succesfull and winner in, say, 1975... can be the very thing that destroys them in 2015. Even if they keep doing what they doing as times changes it makes good decisions bad ones.

And if they can't change and they can't keep up, then they die.

All of this is why we see a lot of "big tech" companies like Microsoft or Apple or Google having to go around and spend billions of dollars buying up small companies.

Because of their size and "ossification" they really have become incapable of serious innovation. If they could be "the next big thing" they wouldn't have to buy up these smaller nimble and more innovative companies all the time.

And if you pay attention to the products they sell... a lot of time they will spend a huge amount of money on buying something that ends up going nowhere because they can't even do anything with it.

I've worked for big companies that are so hard-up for finding "new things" and "new talent" that they will buy up smaller companies just to get their employees. They didn't care about the product at all... they wanted the employees because they lost the ability to find them on their own.

Organizational issues are a serious problem.

All of this is why "economies of scale" and "efficiency" is not a given. It may be true one day, but not the next.

Big factories that one year are revolutionary and making money hand over fist... in later years become such a drag that the company can't even sell them. So they just end up abandoned because they cost more then they are worth.

So when you have governments step and "decide" who is the "market leader"... There is a chance they could be right. But they might be only right for a short time period. Or maybe a long time.

It really becomes little more then a guessing game.

Were as if you depend on market forces big companies come and go and their assets get sold and incorporated into more efficient firms and things evolve and change based on what is needed by customers in a dynamic environment.