I don't understand the disadvantages yet except environmental concerns.

As you point out, PoS basically solves the environmental concerns. (Some people might say it still consumes too much power but I disagree, I think power consumption under PoS is acceptable).

This is just my opinion, but I think the big disadvantage is cryptocurrencies are a pain in the ass to use. Lengthy story about what a pain it's been to use them in Spoiler tag. I think this story is a bit of an outlier since I hit all of these issues, but the fact that a technically inclined person who is just getting back into cryptocurrency after a long hiatus can have this much trouble with it does not speak well use ability or safety.

::: I have a few coins I mined back in the day (before switching all my computing power to BOINC), and I saved off my wallet.dat from those wallets. I wanted to use them recently, so I reinstalled the wallet software. That worked, but then I had to download the entire chain again, so I had to wait more than a day to actually use the coins. Putting cash in a bank is faster if I'm already a customer of the bank. If I'm a new customer I might have to wait, but the point is cryptocurrency doesn't have a clear advantage here.

The coins I had weren't Bitcoin, but the shop I wanted to buy from only accepts Bitcoin. So then I had to exchange mine for Bitcoin and pay transaction fees. I guess you could say it's my own fault for holding a less-popular coin but I'm not sure cryptocurrency is living up to its own hype if there's exactly one or two coins that you have to use, just like how in the US there's no real alternative to USD.

I found a no-account exchange, and I had to carefully enter keys and figure out amounts of coin > BTC. And I had to trust the exchange to give me what I wanted. If the no-account exchange didn't exist, I would have to create a whole new account on a website I don't entirely trust just to exchange one coin for Bitcoin. That's a layer of trust in a "trustless" system. I also don't like creating yet another account with my info in it — yet another way that cryptocurrency is not better than traditional finance.

Then not only did it cost transaction fees, it took hours for the transaction to go through. I could pay more for it to go faster, but now we're talking about fees that far exceed those of credit cards or regular money transfers. Then I had to send the Bitcoin to the online store and wait for that transaction to clear. More time and more transaction fees. The purchase worked without a hitch, but it wasn't any better than using a credit card.

I had to buy extra BTC because it's really difficult to know exactly how much you're going to pay including transaction fees, so after the transaction went through I tried to turn my remaining Bitcoins (I think it was worth ~$13?) back into the kind of coins I keep, but I set my transaction fee too low and the trade I set up expired before my coins went through. Luckily I had given the exchange a refund account, but that meant I had to wait over 24 hours before my transaction actually happened, and then the exchange had to send back my Bitcoin, incurring fees at each step.

While waiting I tried to cancel this Bitcoin transaction, but the software I used didn't support that. So then I tried to extract my private key to enter into another piece of software, and that was surprisingly difficult. I thought cryptocurrency was supposed to put me in control, but without a LOT of technical knowledge I was just as powerless as I'd be with a bank that froze a transfer. I asked for help on a few forums and some people tried to help but the whole thing was confusing and eventually I had to give up and just wait for the transaction to go through.

Then I had to do the BTC > mycoin transaction again, and this time I think the fees were 5-10% of the amount I was transferring. That's way more than Venmo's immediate transfer fee or even credit card fees (I think those are around 3%?).

I will say that during this process I discovered the Electrum wallet, which is very good and works on a lot of platforms. Some of the issues I had would not have happened if I had used that all along. But there are so many wallets out there it's hard to know which one is best and obviously when I started this process no one told me it was the best. And maybe it's not and that just my opinion.

In summary, I'm interested in cryptocurrency and kind of enjoyed using it in the way learning new things can be fun. But it was slower, less convenient, and more expensive than regular currency. Cryptocurrency boosters are going to have to improve all of these problems before it's competitive with regular currency, and I don't see a lot of discussion about how much these pain points suck and how to improve.

:::