All costs are opportunity costs. What is the difference in cost between one set of possibilities and another set of possibilities. Unfortunately human cognitive bias cannot easily make these judgements because we have dense information about the present, and sparse information about the alternatives. Plus we are loss averse, and skeptical of one another.
The christianization of the west is probably the greatest crime in history followed by the muslim conquest of byzantine and Persian empires, and followed by the cosmopolitan pseudosciences of the 19th and 20th centuries: marxism, freudianism, Keynesian innumeracy, postmodernism, and the socialist enfranchisement of women and their destruction of the family, law, property rights, and history, grammar, logic and truth telling.
Lies, damned lies, and more lies.