Bitcoin still traded and i think thats indicating bitcoin is not a buble. I think its called buble if bitcoin price become zero and no one trade bitcoin anymore. Its true that bitcoin price drop and many investor moan about this but i think its very usual in any market that the price always volatile
A simple logic indeed, we need to see bitcoin to completely disappear so that bubble thing will proven, as long as bitcoin still exist and there's still people who's willing to buy and trade from this industry the journey to success being an alternative currency still exist and bubble claimed can't be proven around,
invest taking your own assessment and make your own analysis so things will be just fine in your future goals.