~snip~
mostly it is because of the market conditions only and moreover anything the market is developing little by little and if the altcoin is in popular situation then it will definitely growing but it will be little slow when compared to the Bitcoin but mostly the demand will decide the value also to develop.
It is not about the popularity but investors will look into is the profitability of a certain coin which is something can't be seen by now with some altcoins and so we can't expect that it will rise up same with Bitcoin. Now, if you are investing those coins, you'll probably get bored cause it will be in slow and slow.