Not guilt. Not sin. Your logic is specious parroted re-hash from George Monbiot's failed thought leadership from the mid-2000's. Carbon dioxide is pollution and waste just like household garbage, recycling, and compost. When you offset you're cleaning up after yourself.

As with more tangible-seeming waste, it's always better to avoid and reduce before paying another party to deal with it. Yet CO2 is demonized because global warming is a collective externality. Because it's invisible doesn't make it intangible. Because the reductions can be counteracted by an entity that's in another location doesn't make a difference, either!