[nradov]

The counterargument is that most developed countries are facing a slow demographic collapse, so those tech companies will eventually run out of new customers and revenue growth opportunities. Not exactly apocalyptic but more like stagnation and malaise. I'm not claiming that will inevitably occur but it's reasonably likely.

[karmakurtisaani]

Also, these companies are valued like growth stocks. Even without the demographic collapse it will be difficult to find massive growth at their scale. Some might do that, but which ones?