Let's unpack this a bit without judgment, because it's actually pretty interesting, at least to me.
First, a few neutral (if vastly over-simplified) important historical facts:
1. This flag is one of several official flags of the Confederate States of America.
2. The Confederacy existed from 1861-1865.
3. The Confederacy was a self-proclaimed nation of 11 secessionist slave-holding states that relied on a labor economy of black slaves. The Union considered the Confederacy illegitimate.
4. The Civil War began on April 12, 1861 with the Confederate attack on Fort Sumter in South Carolina.
5. The Confederacy fought the Civil War because it wanted to maintain a system of slavery, primarily for agricultural economic reasons.
6. The Confederacy lost the Civil War in 1865, and slavery was abolished and made unconstitutional that same year.
7. Today, all the previously Confederate states are part of the Union and there is no legal or constitutional difference between them and the rest of the United States.
So that's the historical backdrop.
As I see it, there are a few options--none of them mutually exclusive--for why you would choose to fly a confederate flag in 2017, ranging from innocently ignorant to intentionally bigoted:
1. You're just a big Dukes of Hazard fan and one hundred percent ignorant of history.
2. You're from the south and consider the confederate flag part of your "heritage" and feel entitled to "honor" it, regardless of its connotations, implications, or impact on others.
3. You lack empathy for victims of slavery and/or like to provoke anger and controversy.
4. You think slavery was a good thing and should never have been abolished.
5. You don't realize that the south lost the Civil War and that the Confederacy were traitors to the country in the most literal sense of the word.
6. You're a big macho "patriot" and don't think people should be slaves, but yet you also don't think it's a problem to display a symbol of treason, losing traitors, and slavery, all of which could not be less patriotic.
7. You fail to see the logical fallacy in #6.
8. You just think it looks cool and badass and don't know, think, and/or care about the rest.
9. You don't know, think, or care about any of those negative historical connotations, so that means no one else will (or should) either.
10. You lack intellectual curiosity and empathy (in general).
11. You're legally entitled to/can do something, so that means you should, no matter what.
This is all I can come up with. But the one unifying feature is this: if you feel the need to display a confederate flag in public in 2017, you have a lot of critical thinking and self-examination to do.