i dont think its a bubble, i believe its people moving into alt coins to give them a try. bitcoin dominance if the market is at 56.6% right now, it was over 62% a week or so ago. Looking at that i dont believe its a bubble that will pop. Total crypto market cap is over 476 Billoin, still increasing.
Also we seen bit coin drop about $4,000 USD last week and recover nicely
Just my opinion :)