[hannibal5]

1. You don't get it integrated with your applications like browser, email software, text editor or spreadsheet by default. This leads to network effect in reverse. if you are only person to use it within your circles, signing and encrypting data and messages you send to others can't be done.

2. Encryption is extra risk for your data. If you lose the keys, you lose the data. People are bad at backing up their data, why they would be better at managing their keys? Being sloppy with your keys means that somebody can impersonate you with more credibility (what if banks would accepting PGP singed orders in email)

3. Value from widely used PGP happens mostly in society level. Encrypting any particular piece of data has negative expected value in most cases.

4. Using PGP requires understanding the basic concepts and using it well is not that easy (lots of pest practices). People don't know any of this stuff. Even public and private key is far out concept for most people.