Everything a capitalist market teaches us is against this, if they don't obsolete themselves before somebody else can then they will fall into obscurity and ultimately lose what they've built, just like other companies before it who didn't.
FAANGS companies aren't at fault for when they're winning a game which is rigged from the start.
And if they do fall into obscurity and ultimately lose what they've built?
- The companies who take their place service the customers/clients they used to have
- The workforce either coast along or move to the (presumably growing) new big boys
- The investors should spot the decline and trade away
The only downside is the company - the brand - slowly dies off. For most of us that is fine; the only parties to all this who will actually lose out are the ultimate beneficiaries/owners, and I can live with that. And presumably they've extracted masses from the company by then anyway.
Its both cultural and economics, but the economics only affect the masters and not the minions (who find alternatives) and the cultural aspect is misguided - individual companies/brands are ephemeral and irrelevant so we the minions should not be invested in protecting them at the destructive (to society) costs of scale.