And we're not exaggerating that "hypervelocity" part, either -- an average HV star moves at a staggering 1.6 million kilometers an hour. So while there might not be any hypervelocity stars with trajectories directly threatening Earth that we know of, one could come hauling ass up into our business in a cosmic heartbeat. Plus, the aforementioned 16 are just those that humanity has found and is able to monitor. You know how many are estimated to be bouncing playfully around our galaxy alone? At least a thousand.
The whole universe is basically a grab bag filled with medical waste.
There's still precious little chance of hypervelocity stars ever being an immediate threat, though: "Cosmic heartbeat" is still kind of a long-ass time for humanity. If we geared up a new telescope tomorrow only to find one coming in from a previous blind spot as close as, say, one light-year away, we'd still have a few centuries before it would fry us, cause a cataclysmic collision within the solar system, and inflict some pretty intense gravitational disruptions. You're not going to be alive in a few centuries, though; that's the future's problem. And really, fuck those guys. All flying around in their precious jetpacks like they're better than you. They deserve what they get.