There are stages of competition that I have seen when it comes to how corporations compete with startups.
First, they ignore it. The competitors are too small to be meaningful. It doesn't affect their business in any way. Ignoring it is the right decision for them.
Meanwhile, the startup builds their business. The absolute best way to get a corporation's attention is not to partner with them. It's to compete with them at the margin. Get to customers they want that they can't afford to service.
The next thing that happens is corporations "invest." I put the word invest in quotes because there are several ways they can invest. They can direct invest in companies via a corporate venture capital fund. But, they can also invest in different ways. They often go to their regulators, investing time and money to try and change the regulations to limit competition. Maybe they change their pricing scheme to crush the startup's distribution model. They can invest in more R&D to try and roll out a new product that captures the market the startup created.
I am not against corporate VC at all. They make different partners than traditional VCs and they have very different charters. It really depends on why the corporation is setting up the venture capital arm. It also depends on how the venture arm is seen by top management of the firm. Sometimes they make great partners. Other times they don't.