Bitcoin is vulnerable to quantum computers?

Yes, most systems that rely on cryptography in general are vulnerable, including traditional banking system. But quantum computers do not yet exist and probably never will exist for a good period of time. If quantum computers would become an immediate threat to Bitcoin, the protocol can be upgraded to use post-quantum algorithms. Given the importance that this change would have it, it can be assumed with certainty that will be reviewed in-depth by programmers and adopted by all Bitcoin users.