Who keeps a large percentage of their wealth in cash?
Worldwide, the percentage is similar.
Of course being unbanked isn’t equivalent but it’s likely very nearly so.
Not to mention, the chances of being unbanked are higher for vulnerable populations, especially those who might benefit from uncensorable money.
The last transaction fee I paid was 33¢, and the average transaction in the last Bitcoin block was 913 bytes, so your internet access speed isn't an obstacle to sending a transaction as long as it's above about 20 bits per second; if you want to run a full node you need at least 17000 bits per second of internet access unless you're using the Blockstream satellite.
Typically I pay US$5 a month for cellphone internet access when I have it, but more commonly I use Wi-Fi in various places.
The fact is that many people hold their wealth in cash, and many of the same people are part of vulnerable populations.
One shouldn’t remove another’s alternatives simply because it’s assumed that the other lacks access or sophistication. Even if true, both potential deficiencies are fully reparable and do not permanently negate the benefits of uncensorable money.
Centralized internet is not long for this world. The Internet is being fractured, both ideologically and physically, right now, by world war.
This only gets worse before it gets better, which probably means mesh networks will be adopted soon enough. Anyway,
This is why adopting distribution of responsibilities is so important in projects like Ethereum — your offline handhelds will be able to make provable transactions without having immediate communication with every star in the constellation, so to speak.
It isn't difficult to set up multisignature wallets, where you can lose some subset of the keys and still retain access to the funds. (It's not easy either, but it's not difficult, and there are companies like Casa and Unchained making it easier.)
Just like someone might keep a couple hundred dollars in their wallet/on their person, a couple percent of their wealth in a home safe, and the majority of their wealth distributed across multiple locations with various failsafes to access it, someone might keep a couple hundred bucks worth of BTC in a wallet on their phone, another percent or two of their BTC in a single-sig hardware wallet in a safe at home, and the majority of their BTC in a 3-of-5 multisig setup with only two keys at home, one in a safety deposit box, one in a trusted family member's home, and one in the custody of their attorney.
I don't think setting up the wallet is the hardest part. The hardest part would be to get into a legally binding agreement with the other parties, that you depend on from now on to access your "wealth", the very situation that crypto-currencies were supposed to avert.
You can make sure they don't have enough of the keys to move your funds without your consent. Making a legally binding agreement that they have to give you access to the key they have if/when you demand it is no more complex a legal task than any other instance where you trust someone to custody something for you.
I never said it was harder. I'm merely pointing out that the proposed solution to this particular usability issue that crypto-currencies suffer from involves reverting back to a web of mutual obligations enforced by courts of justice, which entirely defeats the purpose of using a crypto-currency.