The defination of an economic bubble says exactly what bitcoin is about.
A market phenomenon characterized by surges in asset prices to levels significantly above the fundamental value of that asset. Bubbles are often hard to detect in real time because there is disagreement over the fundamental value of the asset.

But if we consider the valuation part, what comes to mind is if this is not the true value of bitcoin then how much is it worth?
If It’s not backed by any physical asset what guarantees it’s future retainment of value?
7.6 Billion people on the globe and just 21 million bitcoins that can ever be created. Ask yourself if the value is justified?
Did it ever occur to you that the technology that powers bitcoin is the best thing that happened to mankind after condoms and Internet?
There were a lot of people who did not understand the Internet back in the mid 80’s and 90’s but look where we are today.
Anyway, I’m a student and I own a very small amount in Bitcoin and other cryptocurrencies and I’ve withdrawn ten times the money that I had invested initially and suprisingly I still have 90% of my profits not cashed out yet. Even if I wake up to hear that bitcoin is 404 Not found, I’d be more than happy that the thing that is taking the world at a storm has ended.
I completely understand the risks associated with bitcoins and other blockchain based digital assets and I have not invested more than what I can play with.
Bitcoin is highly volatile and controlled by a handful of investors. The price making mechanism is on their hands because the retail and individual investors own a very small amount of bitcoins.
Bitcoin is a threat to the world economy and I say it loud. The government of a country should be given the complete autonomy to control funds and allocate resources, failing which the economy can suffer huge turmoils and break downs.
But we cannot overlook the technology that powers bitcoins, Blockchain can be used in future to build more user products and services.
This should answer your question.
Hope that helps.