I think that Bitcoin has many similar issues in the real world, though you might argue that these are more under the user's control.

For example, it seems like most people don't hold their own keys. I know, "not your keys, not your coins," but it does mean that Bitcoin doesn't provide that kind of safety for most of its users. Even if you do hold your own keys, there's a decent potential that you'll lose your keys. I've known people who have lost Bitcoin that way. If you're holding your keys yourself, how are you keeping them safe? You certainly need off-site backup and probably a weak enough password protecting them to be sure that you won't forget the password. People have those key safes that only allow a certain number of tries: https://www.bbc.com/news/technology-55645408. That guy has $240M locked away. Sure, PayPal feels unaccountable when you're a tiny player who uses PayPal for thousands of dollars, but a lawyer would be able to get that $240M.

From that article, "Currently, about $140bn worth of Bitcoin is lost or left in wallets that cannot be accessed, according to cryptocurrency-data company Chainanalysis." Given that Bitcoin had around a $700B market cap back then, we're talking about 20% of the total Bitcoin out there simply being lost.

Yes, in theory, these are things that you as a user have control over. But human life is tough. If you get in an accident that impacts your memory, do you lose access? If there's a fire, do you lose access? If you die, have you prepared a way of transmitting those Bitcoin to your heirs - and a way that doesn't give them access currently? How would you do that? "Here's how you access the private keys, but pinky swear that you won't until I'm gone."

> no one can ban you from the blockchain

I'm not so sure about that. Bitcoin are traceable. The government could blacklist certain coins they determine are the proceeds of criminal activity. Sure, the person holding those coins could still transmit them to others and then those people could transmit them to more people, but if the US/EU blacklisted certain coins, people would refuse to take them as payment. For example, Mt. Gox froze accounts that deposited Bitcoins that were known to have been stolen.

Let's say that the US says, "no business under our jurisdiction can do business with any wallet that has held Coin-X after today." The value of that coin becomes much lower than any other coin. You can't accept that coin as payment if you're looking to change it (or any other Bitcoin you own) into dollars in the future. Coinbase and other companies couldn't do business with you. Let's say the US takes it one step farther and says "any coin held by Wallet-X today is tainted and any wallet that accepts any of the coins held by Wallet-X (no matter how many transactions removed from Wallet-X) is also tainted along with all their coins." That means that everyone in the Bitcoin network needs to treat the coins in Wallet-X as radioactive. If you accept payment from Wallet-X, you now can't convert your money to dollars at Coinbase or similar companies. Even if you accept payment from Wallet-Z who got the coin from Wallet-Y who got it from Wallet-X, you're still compromised. There'd need to be an updating blacklist of coins that couldn't be used by US companies - a list that would expand over time. If Wallet-X had Coin-X and sent it to Wallet-Y, it would taint Coin-A and Coin-B in Wallet-Y which means even more Bitcoin are now blacklisted by the US.

Even if you never want an off-ramp from Bitcoin, others do. Maybe you dream of making every transaction with Bitcoin for the rest of your life. Still, the value drops hard if others don't share that dream. Even if you never want US dollars, let's say you want to buy a house with Bitcoin. The US sees the purchase and seizes the home as the proceeds of illegal activity.

The Bitcoin network generally treats all coins as the same kinda like how we treat all dollar bills the same, but our dollar bills all have unique serial numbers and similarly different Bitcoins can be differentiated from each other. If the US government starts blacklisting coins, they aren't technically banning you from the blockchain, but they kinda are for all practical purposes. Sure, there are ways to get US dollars that don't involve Know-Your-Customer US-jurisdiction rules. However, the value of Bitcoins that are blacklisted like that, especially if they taint your other Bitcoin, goes way down.

Sure, you can't be banned from the blockchain. However, if the US government bans all coins in your wallet, you're going to effectively lose those coins since others aren't going to want to accept those coins.