Yep, I think they're in a bubble, but they're still rising in actual value (overall).
Many are though, and the recent upshot of Dash etc could well be a bubble, but it could be awareness. I dont know which it is.
That's the bit that sucks... by the time you know whether it's legit and feel like you should go all-in, it's usually too late. I was going to buy about £500 worth of Dash at $12 but decided to sit things out. The price started rising, but I kept sitting things out because it looked too steep to me... it HAD to drop. But it didn't. And just kept going. Now it's at $90+ dollars and I've still got mixed feelings because I don't want to be the greater fool. But I do understand that it could potentially keep going up. I've decided to diversify smaller (in market cap) but promising alts for now and not rush into things so I don't get burned (I'll likely see greater % rises elsewhere, too, now that the Dash train has left... but I'll buy if the bubble pops because we've now seen where it can go).
But I digress... I agree that just because something rockets up doesn't necessarily mean it's coming down. It TENDS to, but like AusKipper said, there are examples like Facebook. Dash has also been very good with their advertising... much moreso than Bitcoin (which has only really received indirect advertising through the news, and most people don't have a clue how it works. Dash's advertising actually explains everything in a way that doesn't chase people away).