Facebook has been around since 2004,
It's probably here to stay for a while yet.
Broadly, up to now, the law provides that you give personal data only to companies that you choose to allow to use it, and they can use it in any reasonable way in doing business with you, plus any way that you have agreed to. Tip: don't agree to let them give it to other people, even for free phone minutes. Do that once and you're damned forever. It's also presumed that your data will only be held where European law applies.
Facebook is located outside the EU and it uses data in very wide ways that many of its users don't think about until things go wrong, so there is a need for legislators to create and impose rules for use of personal data to protect citizens from amoral private interests. They might be just able to limit the power of government itself to spy on you, also, but don't count on it.