You don’t need to wait to see how something turns out to know whether doing it is ethical or wrong.
You don't need to wait to see what effect tariffs have. Imposing them is unethical because they are a tax, and taxation is theft.
You don't need to wait to see if the next anti-gun rule reduces murder or suicide, because disarming people is wrong.
You don't need to wait to see if banning food dyes- or mandating vaccinations- improves "public health", because such edicts remove personal options concerning personal health decisions. This indicates you are someone else's property- a slave. Slavery is unethical.
You don't need to wait to see how ending drug prohibition would turn out. No one has the right to control what someone else consumes; doing so anyway "for their own good" is wrong. As is criminalizing defending yourself and your property from those under the influence of drugs.
When doing something you have no right to do, the only reason to say you need to "wait to see how it turns out" is because you are addicted to controlling things that are not yours to control. You are rejecting ethics in favor of pragmatism.
Thank you for reading.