Short term they seem like a way for a small group of early investors to dupe newcomers out of their money. It sets off my scammy sense.
Long term the fractionalization and marginalization of "everybody has their own cryptocurrency" thanks to the flavor of the week varieties is going to cause a slow devaluation of all of them. You get the hot and trendy new one supplanting old ones on actual investment, only to cause massive fluctuations in currency values that will make the Somali shilling look stable.
What do you call a currency that can magically lose a third its value in 24 hours just because the Christmas shopping seasons ended? Bitcoin. What's the largest the dollar has ever fluctuated in a day? A week? 8% MAYBE?!?
Slow spikes like the Dec 15th one and bottom falling out just a week later do NOT make for a trustworthy monetary system. Money is like a tsunami, when all that water goes flowing out to sea creating the lowest tide ever guess what follows. The slow climb in value has a plateau as more people use it, but the whole system is as volatile as stocks... and there's a reason playing the market should be called gambling, not investing.
To be brutally frank, it FEELS like a Ponzi scheme; overselling something that doesn't exist. Admittedly "real" money is in many ways precisely that. It's only worth something as long as we all agree it is worth something... but I feel better having a government and regulations behind my money than "hurr durz its bee cumpletelies decentralized"
That damned near every software I've tried for it has basically broken the machines I've installed it on requiring a complete wipe and OS reinstall didn't exactly inspire confidence.
Though maybe I'm just getting too old for this **** -- but I don't know a lot of people over the age of 40 who trust the CONCEPT... I know a lot of twenty-somethings yumming it up like the latest get rich quick scam from Mary Kay or Amway.
I may be wrong, but it feels less legitimate to me than faiths...