We never know when enough is enough until we go too far:

In fact, we have reached a tipping point where technology is now destroying more jobs than it creates. 

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Traditionally, elements like productivity, jobs, hourly wages, and income all grew in unison. However, during the last 30 years GDP and productivity grew while the US median income stopped and employment flattened, Wallach writes in his new book. Technology innovation has played a significant role in this trend.

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Obviously one solution is to go even farther.  Apparently that's the one we're choosing now...

So, for example, in 1990 GM, Ford, and Chrysler brought in $36 billion in revenue and hired over a million workers, Wallach said. The big three today — Apple, Facebook, and Google — bring in over a trillion dollars in revenue and only have about 137,000 workers, he said.

This change has created a situation where more and more of the capital is going to a smaller percentage of the population. In fact, we are on course for 70% of stock ownership to be held by 5% of the population, Wallach said.  

This is a dangerous scenario because it could potentially lead to massive social unrest, possibly even revolutions. 

My question is why more companies can't do what Apple, Facebook, and Google do?

Or is it winner take all?

There are lots of ways this could go. The most peaceful would be gradually moving to a guaranteed income for all humans, with robots and A.I. doing all the labor; then an eventual merging with the machines. More likely is some kind of violence, with the very rich using robots and A.I. to dominate most of humanity. To be honest I don't see the Terminator/Skynet route where human extinction is the A.I. goal as likely. I'm hoping for the peaceful route, but I don't have a lot of faith in the wealthy. 

I'm hoping for the peaceful route too.

I'm guessing the more of us who want this, the more we can make it so.