blockchain is a part of bitcoin, like death is a part of the life
Death is the absence of life. Are you saying that the blockchain is the absence of bitcoin? Or otherwise?
It's reversed. bitcoin is a part of the blockchain. Let's not forget that Bitcoin is a trustless consensus - currency is an app or extension of this consensus. bitcoin is stronger than just a currency - the blockchain can serve as the backbone to all future endeavors that need a 3rd party as a consensus.
It is just my opinion (and nothing else) that the blockchain should be exclusively used for money.
That's like buying a computer solely for the purpose of checking your email.