A couple things here

1. it's pretty unlikely that the systems we've sent messages to have civilizations in the first place. The rationale that certain systems may have life doesn't mean it would have a civilization, so our efforts in METI are really unlikely to stumble across someone.

2. Our location is already known by any reasonably advanced civilization. In the last couple decades, we've already found thousands of planets across thousands of light years. Our technology is getting good enough that we can start to look for biosigniatures, and there are even concepts like the solar gravitational lens, that could allow us to not only image, but map entire planets as if we had probes in the system (possibly even allowing us to spot city lights and other technosigniatures). And that's with technology we have now, or can develop in the next couple decades. A civilization capable of just ubiquitous interplanetary travel could easily map their section of the galaxy, and have, on record, every planet with life, and every planet with a possible or known civilization. That will include us. And that's not getting into civilizations capable of interstellar travel.

Acting like we're doomed because of a few messages is misguided fear at best, and concern trolling at worst. If there are other civilizations out there, close enough to reach us, they already know we're here. We don't need to send out messages for them to know that. So we have nothing to lose and everything to gain by attempting contact, because if someone is willing to respond, I'd wager they're helpful in the first place.

Interstellar travel is hard anyway. It can take decades or centuries to reach distant stars, even with the best technology, so the idea that a civilization might attack others isn't really a cause for concern. If there was anyone malicious out there, I refer back to my second point, in that they already know we're here, so as morbid as it is, there's nothing we can do about it. But seeing as life has been around for bilions of years, and our civilization has been allowed to exist up to now doesn't look to me as though there are murderous civilizations out there rabidly wiping out any life.