The 'big five' could destroy the tech ecosystem

If Amazon puts retailers out of business, who will advertise on Google and FB?

How big can the largest tech companies get? How completely can they come to dominate the economy? The “big five” — Apple, Alphabet, Microsoft, Facebook and Amazon —now have a combined valuation of over $3.3 trillion, and make up more than 40 per cent of the value of the Nasdaq 100 index. As the digital economy continues to grow faster than the old economy, it’s hard to see what can stop these juggernauts. Unless reality intrudes.

After all, what exactly is their business? Who are their customers? What role do they play in the economy? Each answer points towards some limit