Why aren't you using crypto as cash?

What properties would a cryptocurrency have to have in order for you to consider using that instead of, e.g., USD? What are the barriers to using crypto in this way today?

Optional background info:

I am currently in the period of coming up with my thesis topic in economics and finance. One of my id eas was a discussion on what properties would a decentralised currency need to have in order to be mass-adopted and perhaps replace centrally managed currencies.

I probably go deeper in the obvious areas that block the adoption:

• volatility
• perception of crypto as an investment (disincentivising spending)
• trustworthiness
• unfavourable future for current financial institutions
• etc.

I am therefore currently interested in the views on this topic so that I can form a general idea about the probable consensus.

Thanks!