I agree that no matter how cautious certain groups are and
will try to be regarding sending messages into the galaxy for
ETI, there will always be some individual or group who will
forge ahead into the darkness, regardless of the potential
danger to us.

That's why we need to prepare for whatever is out there as
much as possible. Even the possibility that no other intelligences
are out there, as much as my gut feeling says otherwise. But
I've only made a few excursions as far as Sirius, so I can't really
say for sure.

But we should exercise some caution before ringing the cosmic
bell, if for no other reason than that our messages into the
galaxy should at least contain some serious chances of being
understood by an alien intelligence, at least if we want some
real hope of a real dialogue and genuine increase of knowledge
in both directions. The Beatles song is not the right way to go,
other than to draw attention to METI.

I am not terribly worried about an alien invasion, not only
because I think the odds are so small due to there being so
many star systems in the Milky Way, but also if someone
sophisticated enough did want to do us in, they could do it
with ease and probably before we even knew what was
going on. We can't even defend ourselves against a random
space rock yet, let alone a deliberate attack.

I like to keep hoping that a truly advanced species would not
be a maurading attacker, if for no other reason that we pose
no serious threat to anyone other than ourselves at this point;
but I can also see us getting pushed aside by a civilization
that has need of the galaxy far beyond the wants of some
tiny bugs on one little planet.