The market cap obsession is part of the problem. Can I use it to buy things, easily? That's the only metric that should count if you're looking for practical use, not speculation.

It's hard to measure that directly. Market cap is a decent proxy, albeit inexact. If a coin has a market cap of $1.8 trillion, you know a lot of people are doing a lot of something with it, and it's likely that includes using it to buy and sell stuff to some extent. If it has a market cap of $200 million, then there just can't be many people buying and selling with it, and that means it's pretty likely to be difficult to use that way.

A successful cryptocurrent probably has to start by first having a market that is dissatisfied with the available traditional currencies. If that market were to introduce on (with good tech), then it could immediately see the cryptocurrency used for its intended purpose. At that point, if it avoided the attention of speculators (not forever, just long enough for it to get its feet underneath itself) or could discourage those speculators somehow, what happens then?

Is there some other failure mode waiting, or does it take off?