Well, we were able to observe in the impact of legalization of online betting in real time, watching every other ad slot during sports games turning into gambling app ads designed to hook 20 something men into lighting their paycheck on fire for a brief dopamine hit.

Plus, prediction markets going from a harmless novelty where people would bet a few bucks on an election into a massive offshoot of gambling industry incentivizing manipulating outcomes/insider trading, once again leaving the average gambler left holding the bag and poorer.

You honestly couldn't design a better experiment to test the theory of whether open and legal vs. banned but underground gambling leads to better outcomes. So I'm not sure why it matters that other countries have different laws (that likely were more thoughtfully designed than basically just saying "it's legal now" out of the blue).