There is nothing stopping people from using it as peer-to-peer cash.

I used crypto sell a GPU to someone I know. I regularly use it to trade hardware over the internet, and I would use it more if more vendors on ebay and such accepted it.

It has low fees, works with open source software, and is pretty straightforward to accept without fear of charge-backs or fraud. The volatility is only a problem in the short term, and I don't mind holding on to crypto despite volatility because it has a lower inflation rate than the USD.

>Ledgers can't scale to allow for a financial system that could serve an entire country either, due to transaction speed issues.

A lot of the issues with transaction throughput have to do with the network parameters of old cryptocurrencies like bitcoin which were optimized for a 2009 internet.

A single ledger can't scale, but if you just boosted the block size of a bitcoin-like cryptocurrency to ~200MB you would have transaction throughput on the order of paypal. If you do payment channels on top of that and/or have atomic swaps between multiple merge-mined ledgers I think that you would have a decentralized payment network which could serve the entire world's current needs, at least for online transactions.