Well, that's the cycle.
Coin gets popular.
Lot of people start mining it.
Net share rate explodes / user share decreases
People do math and think the ROI is low so switch to something else
Net Hash rate goes down /user share goes up

At least with HVC we don't have to worry (yet) about auto-switching pools and dumping/exchanging coins which hurts the value of the coin.

It really comes down to how you mine.  Do you mine and quickly sell or hold for future speculation of profit?

Keep in mind that it can make a lot of sense to mine "at a loss" for now if you are holding your coins.  If the coin being mined now is worth ten cents but in 3 months is worth 60 cents...
Of course the coin worth 10 cents now could be worth 1 cent in 3 months too...

Not sure that really helped, but that my 2 coins worth of info.