As I understand it, SETI was never really concieved as one of those things
that are undertaken because there's a "good chance" that success will be
gotten.  For all we know, Earth might be the last house standing or the
first house to be built and moved into.  We might be the earliest
intelligence in the galaxy, or we might be the oldest remaining intelligence
in the galaxy.  I think that when figuring the costs of trying to listen
with our ear against the wall to see if we can hear the neighbors talking,
that although the feasibility of what's being proposed should be a concern,
it shouldn't be the main concern.  SETI's main goal, at least in my opinion,
is to answer the question "Are we alone?"  Not the question "What do we tell
the bean-counters to get funding?"

By the way, when I was a wee lad and count my birthdays with one hand and
some fingers, and Congress slashed the SETI budget, I wasn't very happy
about it and thought it was inane governmental bean-counting at its worst.

And even if we do find we aren't alone, and they do turn out to be not too
friendly towards us, at least we know that life isn't a fluke in the
universe.  That's quite a good thing, no matter their disposition.