Personal data is property. As such it is subject to property law and also copyright law.
Data Property Rights
Naturally, the laws that apply to property apply also to data. Data is unusual in that it can be stolen by copying as well as by direct theft. The violation of copyright by copying personal data without permission is thus theft. This is the case even when personal data, for whatever reason, is in an unprotected copyable state.
Copyright laws apply. Individuals may choose to share some of their data under a creative commons or open-source license, in which case those arrangements determine its use. That is the choice of the data owner.