Fiat doesn't work on a finite planet. Crypto has failed on its goals. What is a better way to be economically secure?

Well, this is a fair criticism... of Bitcoin :)

It's supposed to be decentralized, but things like mining pools have lead to heavy amounts of centralization in block production. If we look at Bitcoin, for an example, we see that over 51% of block production is controlled by just two mining pools. That's not limited to just Proof of Work mining either. Proof of stake sees centralization in staking pools as well. That's only just looking at one aspect of the network

Centralization of mining pools (and mining in general) is indeed a serious problem. In Monero we now have p2pool which is totally decentralized. For now it's just shy of having 10% of total hash power, so there is a long road ahead, but we are moving there. ASIC resistant RandomX also helps to ensure mining decentralization.

It has also not really been seen as a currency. People's view of it as an "investment" which have the opposite qualities you really want to see. People are encouraged to hold it and never let go, meaning they won't want to spend it which is adverse to its use as a currency. This has also lead to it being incorporated and dominated by the very financial systems it was initially supposed to move away from

I don't think this applies to Monero, which is more or less the only currency used in DNMs.

Proof-of-work has inherent centralization pressures due to economy of scale. You get more profit per hash per second of mining power when you've got a bigger mining operation. That's not the case for proof-of-stake.

There has been significant growth of crypto as currency, particularly in the developing world with use of USD pegged stablecoins. It remains the only practical solution to make online transactions privately or when alternatives have been censored, potential pitfalls notwithstanding.

Centralized control is a threat, but it's one that is taken seriously, and by practical metrics crypto has been largely successful in defending its integrity here. Other related values measures worth looking at are credible neutrality, permissionlessness, and trustlessness, also basically areas it continues to succeed. You submit a valid transaction to a major blockchain, it's getting included, even if powerful people would rather it wasn't. Transactions that are illegal as per US sanctions are treated more or less equally to any other. Miners and stakers are not taking control of the money printer dial for their own enrichment. And there's reason to think this will continue, because in a lot of ways control is a liability, and giving it up is valuable; "CEO of Bitcoin" is not a sane title to aspire to because it would make you the responsible party and valid target for all sorts of legal threats and obligations, and just having it would destroy the value of what you control.

That said, as a means for the economic salvation of the median person like OP seems to be talking about, it was never going to do that on its own, no one who thinks honestly about it would promise that, and anyone who did is full of shit. It's just a new type of p2p money with some cool properties, that obviously isn't going to be enough to fix the mess that is the world's economic and political systems.

XMR is decentralized and its seen as a currency