Well in economics, bubble is when a stock or in this case an asset goes up really high than it intrinsic value, then it will crash down. But economist or bashers they really do not know the intrinsic value of bitcoin. Since it is fairly a new technology they do not have any asset that they can compare it to.
Bitcoin was already accused of being a bubble eveytime value goes up but look at its value now.
bitcoin is not really a bubble and it is just normal for its value to increase or decrease because thats how it works and people who are into the world of crypto knows it or maybe they are just butt hurts and noobs and want to make anything just to discredit bitcoin. but no matter what they call it or what they do, most of us are still believing on bitcoin.