Mom's helpful post aside: immigration always involves taking risks. You're leaving behind everything you know and are familiar with. Some risk-averse people need a bit of persuasion for that, but others just never manage to settle in a new place and always regret moving, or end up going back anyway even if it's somewhere "objectively" not as good to live in s the US. It's commendable that you are looking to give your brother all the information he needs to make a well informed decision, but ultimately it has to be his decision.
Yes I know,...the final decision is his. Actually, I am the one advising him to take his time to weigh the pros and cons and base his decision on a series of well-informed factors. At first he told me he was 90% sure he wasn't willing to go any further with the process , after that he told me he was now like 50/50%,...I told him to wait until September and not send DS260 form until he's 100% sure. Meanwhile he could gather as much info as possible, so his decision would be based on rational considerations, not impulses. And yes, I already warned him it wouldn't be easy, but the reward will be worth it. Now he has to consider if he's ready to suffer one more time for a bigger reward or he prefers stability.