why does an atom wants to achieve noble gas configuration at all?

Hello Student,
All the noble gases have fully filled orbitals. As their orbitals are filled, they need not to either loos or gain electrons i.e. they do not react further. This means that they are very stable.
In science, it’s all about stability, all the atoms, molecules or ions tend to get maximum stability, and they lose or gain electrons or react with other molecules in order to achieve the stability. This stability is achieved when their all the shells or orbitals are fully filled just like noble gases.