Bitcoin have a secured protocol and unbreakable security.from the start and at the present day . They did not do any type of scam's and the most important it is decentralized . And not under control of any governance. Do that make it more trustable.
you are right, that bitcoin is famous for its decentralization and is not under anyone's control so that no one regulates it for the benefit of individuals or institutions. bitcoin moves because trading transactions have taken place in real terms and its security so far no one has been able to crack or even intervene. so it is natural that bitcoin until now is having a very high trust and no one is afraid to invest at any time.