Insurance are given to things which are centralised, and that is enough I think to explain. But to further elaborate, insurance is a product of regulation from a third party. Given the decentralisation in its nature, as we are all aware of it is quite impossible.
Is there any chance that bitcoin can have an insurance from its vulnerabilities in the future?
Bitcoin will only be vulnerable if you will mistakenly send it to other wallet for no reason, and also vulnerable if you lost your private keys. If you will observe these two are mistakes being made by the investor or user, therefore they take full responsibility of their holdings, with no one to blame if something bad will happen.