A very stupid take. Running mail infrastructure requires technical knowledge. It requires ongoing maintenance. People avoid it today because it is and always was difficult. Complexity lies with things like SPF, DKIM and DMARC. All which require custom configurations to interact with the mail network.

Even running a Bitcoin Core full node is trivial compared to Mail, it requires no out of the box configurations. Download, run it, sync the chain. I would not accept the argument that running a full node is like running a mail server either, its significantly easier, but does require some resources (fast net connection, storage for blocks, etc).

Running a self-custodial wallet, and recording the seed phrase, like with Blockstream Green Wallet, is a basic thing that everyone on the planet can do. The level of complexity is somewhere near "install candy crush" and "use a pen and paper". Trivial for billions to do right here and now, today.

Don't let these morons come up with excuses. Install an app. Write down some words. Any idiot on the planet can do this.