Corporations are a form of business that are built to rely on infinite growth in order to remain stable and operational. Profits over time MUST increase, or shareholders will lose confidence and sell stocks, resulting in the stock price falling and potentially setting the corporation into a death spiral.
The problem with this is simply that we live in a world with a limited quantity of resources, and a limited number of people. So, what does a corporation do to continue growing once it has gained a dominant position in its sector? It must either diversify into other sectors and markets, or kill off/absorb all other competitors in its sector. This is how multi-national conglomerates, monopolies, and corporate trusts form, and this is the reason we are seeing several Megacorporations (Multi-national, multi-sector, monopolistic corporations) taking form in our modern age.
Disney, Google, Amazon... Such corporations have come to be woven into every aspect of our lives, and most of the time, we're barely even aware of just how much ground we have ceded to them. When will we say enough is enough?