Why not import a certain number of apex predators to a specific country and let them all duke it put. Local conditions and wildlife be damned.

I nominate your country. That's essentially what open borders would allow. After all, no borders then no animal importation restrictions. Hell all the criminals of the world could use it as a central shipping location for sex trafficking, drugs, illegal animals.

Your ideals rest of the idea that humanity is only ever moral. Humans are that way though. Hence all the billionaires.