[thesuperbigfrog]

>> Isn't that only about separating government powers?

Yes.

However, non-government economical powers are subject to laws created by the government.

Anti-trust laws and anti-monopoly laws in particular were created to address problems where non-government economical powers become too powerful. These laws fall under the Commerce Clause (https://en.wikipedia.org/wiki/Commerce_Clause) of the US Constitution.

The law doesn't guarantee that people will be prosperous or happy, only that they will be free from an overly tyrannical government.

If a US citizen feels that a non-government economical power is too powerful, they should work with their elected representatives to make laws to restrain those overly powerful non-government economical powers.