It's a little too simplistic and inflammatory. One, find a country that didn't "steal land". Even the great Kingdoms of Africa grew by war and "stealing" land. That's not to excuse or justify their history, but then why should only the US be held to this? Two, less than 5% of Southerners ever owned slaves, slavery wasn't limited to blacks and blacks owned slaves themselves. Third, the same economy "built by slaves" (quotes because there is more to this simple statement, its wasn't built exclusively by slaves) was dismantled and destroyed by 1865,  via campaigns like Sherman's March to the Sea. A further 150 years of history have transpired since (impact of Jim Crow laws on the growth of the US economy is a different debate)  If you want to castigate the Confederates, what does that make of the tens of thousands of Union loyalists who lost their lives fighting slavery? It's not so simple to say "America always and forever bad because slavery!"