Big Tech is fundamentally the result of two things:
1. A favorable regulatory environment for owning everything (e.g. lax antitrust, little to no ownership restrictions, open international markets)
2. A favorable creators' monopolies regime so that everything can be owned (e.g. absurdly-long copyright terms, patents that cover round rects, etc)
The first term makes it possible to buy everything under the sun and the latter makes it advantageous to do so. We've already seen this in media; but Congress likes the idea of having Disney be the cultural imperialism arm of the US Government. Congress also liked the idea of Big Tech being it's propaganda arm for a while, too; until they realized that Big Tech wasn't going to play ball in the same way Hollywood does.