It’s the lack of user focus. Setting up a bitcoin account, understanding the security implications, hardware wallet, secret keys, the whole enchilada is too big for an average consumer to digest.
Somewhere in Jobs’ biography by Walter Isaacson, there is a snippet about how products often fail when they’re designed by geeks, engineers and technology people - they make products to sell to customers that are like themselves. I’m an engineer myself and I also think the contrary is also true - products and services developed by “MBA” kinds often fail because the people in charge of the company roadmap have no fucking clue about the technical details and trade-offs of the product.
Bitcoin transaction process is designed for the most part for the nerds, not for the average Joe. I know there exists Coinbase and other “easy” setups for Bitcoin. But I’m talking about what happens when an average joe Googles “How to setup a bitcoin account”. Instant “nope” - I don’t have time for this shit and my personal money is at stake if I mess this up.