What you seem to be missing is that the barriers to entry for modern technologies are incredibly low (and getting lower). From basic microeconomics, we know that the ability for a company to maintain >0 economic profit for an extended period of time relies on them maintaining a competitive advantage - barriers to entry help a lot with that.

Today, disruption is so easy. Starting a app/website/platform involves almost no fixed costs and variable costs scale easily. We are now seeing century-old corporations being disrupted by university students. Technology has helped this situation, not hindered it.

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