Why did Americans steal land?

Why did Americans steal land from the natives?
Please teach!

It wasn't the Americans who did it. The Europeans have had a very war-torn history. There were many many countries placed relatively close together, and the techniques of war had been honed over the course of a thousand years. Therefore when the American continent was discovered, they rushed to see who could claim it first. After all it would be a huge advantage -- think of it like playing Starcraft, and coming upon an empty place to put a base. You would want to make your own base there before anyone else did.

However the Europeans went there and saw that there was already a population of people living in this area. The thing is, many of these people didn't have the level of technology that the Europeans did. As a result the Europeans were able to kill off a large amount of the people.

To those civilizations that did have a level of technology, or a population large enough to pose a threat even without technology (omg zerg rush), the Europeans ended up spreading diseases that the American Indians did not have any defenses for.

Therefore once all the Indians were gone the Europeans were able to set up their warbases. Some people in the land then decided to form their own country and go to war against everyone else who was on the continent and so they ended up owning it. Also they decided to buy some other parts of land from other countries.