You don’t look at the material reasons why things change , and kind of tried to change the topic here to justify your beliefs . As you admit , the United States was founded on libertarian principles . A lot of the founding fathers didn’t agree with slavery, but they also didn’t think it was their right to tell other people what to do .
You don’t care about the scientific and material reasons why things change . Slavery was abolished because it was less productive then wage slavery. Wage slavery you don’t have feed the person, you don’t have to house them, their entire life is up to them and you can get rid of anybody you want at any time .
Also every country in Europe had already banned slavery, and they were starting to boycott the USA for still enslaving Africans .
This is why colonialism and imperialism is so important . We lost our slaves so we needed new slaves. That’s why Europe and the USA started invaded foreign countries and overthrowing their leaders, to create foreign slaves that could be unseen and out of sight . This is why so many nations around the world are in such utter devastation, because they have been being used as slave colonies for hundreds of years now and many to this day .
You speak about libertarianism likes it’s also humanitarianism . You cannot have your cake and eat it to no matter how much you want to. Ayn Rand never believed that libertarianism means all the poor people become happy and free.
Capitalism and libertarianism is about the strong destroying and enslaving the weak . That’s what it is, please just be honest with yourself and realize the 2 sided nature of life .