This is a fair argument, although I don't know why people would store their wealth in monero instead of bitcoin.

I can't also grasp how monero is supposed to scale globally onchain...imagine 2B people using it: would that be even possible without centralizing too much the consensus aka the block storage and validation?

Can you point to some monero-related resources that discuss this matter?

To me it seems that monero and other privacy coins are somehow interesting playgrounds, but would suffer of exactly the same scalability problems of bitcoin if adopted widely.