BRICS is a house of cards, the amount of problems that may arise from a variety of reasons on their members are simply to many.

Also, most of these numbers are made by China alone, and they'll face huge economic challenges ahead. India might be the next big superpower in few decades but the amount of social problems must be taken into consideration.

Russia, at least for now, is doomed. Brazil is kinda alright but political turmoil and high public debit puts everything on halt. South Africa is the least I know something, but I don't think is any better than the others.

All of them suffers from some lack of transparency, corruption and/or severe political issues.

You could argue G7 also suffers from severe public debt, but everyone does nowadays. You might not like government on these countries but, trust me, the worst of the G7 is certainly lightyears better than the best of the BRICS.... Don't be fooled, BRICS is just propaganda... At least for now, there isn't any true pact between BRIC members.

Not to mention the tense situations between China and India...

GDP is one thing, GDP per capita is another, and then the distribution of the GDP through currency creation and interventionist policies is another prospect entirely.

lol, its literally just China and India (who were having a border dispute in recent memory lmao)

Source:

The Rise of the BRICS https://www.statista.com/chart/30638/brics-and-g7-share-of-global-gdp https://www.zerohedge.com/geopolitical/rise-brics