To the uninitiated cryptocurrency is daunting. Most people have only ever heard of Bitcoin, nevermind the thousands in existence. The terms: blockchain, p2p, forks, decentralisation. Totally lost on them. If cryptocurrency is going to become common use, it's going to have to become idiot proof.
Stability
Before the average person starts accepting and investing in a currency its going to have to be stable. Either artificially or potentially its own strength against fiat.
While great for trading, nobody wants to depend on a currency that one day can buy you a car, the next an ice cream.
Easily recognised value
Have you ever seen a tourist trying to calculate an items worth in their native currency?
Without using a convertor tell me what 0.000054 BTC is worth. Same issue. And it's an issue that will have to be overcome before a currency is widely accepted.
Physical presence
I'm 31. I'm aware that my phone can do NFC payments but instead I use my physical debit card. I don't even know why I haven't set it up yet, maybe it's some deep underlying mistrust.
If I'm this way, imagine the resistance from older generations that still struggle with emails.
A cool theme noise
You know, like the Netflix thud, or the Mc Donald's whistle. I propose we collate all the screams of everyone that bought BTC at $40k into a single 2 second clip.