In order to settle this country, we forced Native Americans off their lands, often making them walk hundreds of miles in winter conditions to their demise. We ruined their way of life by killing their wildlife, taking their prairies, and restricting them miniscule tracts of land that couldn't support life. We forced them to react and then called them savages for doing so. And yet, the first settlers were warmly greeted by Native Americans and likely wouldn't have survived without their help.
In short, this country would not be what it is without the sacrifices of those who lived here before us. It is the biggest crime of US history. The least we could do is recognize their contributions and our errors in a national holiday.