None. It's not meant to be an investment, it just happens to be used like one currently.

It's ironic, the same thing that makes these coins valuable to people (volatility, and mostly in the upwards direction) is a major reason why they are hard to use for mass transactions.

However, there is some good here. People are getting familiar with crypto by participating in this investment strategy. A relatively stable coin capable of high transaction throughput and low fees - one that can actually be used as a currency instead of an investment - will benefit from this in the future.