The first question is kinda encompassed by the rest of the structure, so I'll work through the others and come back to it.

Legitimate currency, is admittedly a nebulous term, so I'll revise this to match something closer to what I meant: minted, regulated currency held to an economic demand. I believe there's merit to this system, though its benefits have been substantially eroded by modern aristocrats.

By my statement, I meant to say that the most popular use-cases are frequently that of investment, rather than good-faith application of cryptocurrency as currency. I recognize this isn't true of all currencies, but as long as it remains the case, crypto will continue to be utilized as an investment vehicle for national currencies rather than as something I could go buy my groceries or pay my bills with. One of the biggest fundamental problems that have been a challenge to solve for cryptocurrencies is the overall stability of its value. For some currencies, the idea was that a limited supply would lead to a fixed value, or that proof of work systems would mitigate speculation. This hasn't proven true. It cannot be tied to someone's needs, and instead floats based on wants or hype. This is remedied by stable-coins, but at this point you've only recreated a national currency with extra hoops to jump through to use it. That said, I do recognize its value as a means to ensure some personal liquidity in nations where the currency at home is more volatile than not, but I think the flaw in this is that no matter what you end up pinning your personal wealth to someone else's economy.

And believe me, I agree people should be able to spend their money how they please. No few should have complete power of the many, especially not in how the many may accumulate or redistribute their wealth. Robinhood, stock exchanges and their third party brokers should not have power to affect this. In a well-regulated context, they would not.

Now let's talk about money laundering and fraud. I wasn't referring to an old mafia outfit. Organized crime has evolved well past that, though I'm sure a shell company with some shady accou ti g is part of the process. Cryptocurrencies are weak for the same reason they are strong. Wallet addresses are at worst, pseudnonymous. It is possible to track them through transactions to exchanges or services with KYC requirements, but not all blockchain services expose transactions transparently. This makes currencies like Monero a popular option for anyone looking to hide the sources and destinations of their payments without needing to worry about how to balance their books for a nail salon. Add in tumbling services for popular cryptocurrencies like Bitcoin, Ethereum and stablecoins and now you've got yourself a very convenient pipeline for shady dealings.

As a privacy advocate, I believe in the ability to make a cash deal with someone without the scrutiny of the bank, payment processor or other entities, but many of those guiding principles have led to the design of systems that directly facilitate scams, fraud, human trafficking and espionage. The fact that there is no oversight means there are no repercussions until that money re-enters a national currency. It's an immensely popular way to hide wealth for those who are already rich beyond their means as well. Everything about it requires trusting the individual, and that's rarely the correct choice.

As for decentralization. I agree here, that's a better approach. The web should be a collection of nodes, with each reaching to the other to properly describe its namesake. Instead, we have the problem of consolidation among services, where large entities with the means to do so have become immovable conglomerates of critical infrastructure, developing a hub and spoke design instead of the web it was first called. However, blockchains by nature risk the same eventuality. A blockchain relies on redundancy. It needs to be able to point to its own history, and then it needs to have copies of that history redistributed among the entire network of users. The problem is that this requirement becomes exponentially more difficult to fulfill as its use and history extends further. Mining needs to be performed to validate transactions, but mining becomes more time consuming the longer the chain. As a result, the ability to perform these tasks is directly tied to the person able to afford the hardware required. There's an initial or ongoing investment required no matter what. Not to mention that the validation of these transaction requires energy. It needs to be done computationally, and the cost of that computation also increases as the chain does. The environmental impact may be overshadowed by present AI training datacenters, but it's still a present and largely unsolved issue.

I hadn't heard of arweave mind you, but nothing in their documentation about hosting a node or being part of the chain itself leads me to believe they have found a solution to this, which is a must, if you are to rely on it as a stable, distributed storage medium. That said, its permanent storage design is intriguing, since it has the potential to address common problems with the bittorrent protocol.

As for complexity, it's as described above. The infrastructure is the complexity. You're right, it's easy to deploy an NFT, but there is no move to standardize on a platform for them. No self-serving enterprise is going to set themselves up on a chain of custody they do not have control over. I admit this is a political complexity, not a technical one, but I think it's a truth to contend with for the same reason centralized services exist to begin with.

As for your last point: I don't believe in NFTs because I fundamentally do not believe in DRM. Smart contracts, NFTs and blockchains on the whole are designed to track, verify, and validate the transfer of ownership in a way that describes and acts as an extension of existing DRM schemes. It goes beyond a certificate of trust, and introduces the limitations of physical property into a digital space. In fact, it doesn't even solve the resale problem because there would be nothing to prevent a vendor from reintroducing some kind of SecuROM nightmare via a Smart Contract.

I think the base technology is important. At the end of the day blockchains are actually a useful technology, with wide application. But the need to have visibility of the whole transaction is the flaw. You can mitigate it somewhat by chunking the chain and holding data in different places, but the data must remain intact.