They already are. And calling the rest of BRICS poor and weak is just overt trolling, but also a probably an indicator of a more genuine misunderstanding of how trade and 'globalism' more generally actually works. For instance Niger most certainly is not a wealthy country, but the 'West' in general is having a fit about the coup there (and getting ready to start yet another war over it) is because in spite of being a small, deeply impoverished nation - they supply something like 25% of all of the EU's uranium needs, at rock bottom costs - in an echo of colonial times.
The only BRICS members with both large and growing economies and militaries are India and China. Calling the others poor and weak isn't trolling, it's just an objective statement of reality.
As for Niger, it's not a member of that bloc nor has it even been invited to join. Regardless of how much uranium they export, they will never have any influence over the international financial and trade settlement system. So, I don't know why you would even bring that up.
I mention Niger both because of your apparent belief that the things we're talking about only happened in the past, and because they're a perfect example of the goal of BRICS. Right now most countries in the world have limited sovereignty. They can do whatever they feel like, right up to the point that it runs contrary to Western interests. But as soon as they cross that line it's time for the old tired playbook of death and destruction: coups, color revolutions, weaponizing "international" organizations, sanctions, outright invasion, funding/training 'moderate radicals', and so on.
BRICS is not about cooperation, but rather about allowing each independent country to fully pursue their own self interest. Right now that's not really possible when relying on economic systems controlled by the US. So we're seeing a gradual shift on the currencies countries hold, US debt holdings, the development of e.g. SWIFT alternatives like SPFS, and so on. The development of a common currency will be the next logical step.
