Why are we still celebrating a "holiday" that is based off of a man that never really discovered America and enslaved and mutilated native people?

The Christopher Columbus statue off of Jefferson and Randolph street in Detroit was vandalized on Monday afternoon. The statue was left covered in red paint and stabbed in the face with a hatchet. My question is...what do people do to "celebrate" Columbus day? Do we take over land that is not ours? I'm confused. I think it's really time to reconsider calling Columbus day a "holiday" and maybe pick something else to celebrate.