I actually find this to be very depressing. Leads to one of two conclusions:

1) odds of intelligent life are so low that numbers like 1/10,000,000,000,000,000,000,000 are feasible, or

2) every intelligent civilization so far has died off without leaving tangible evidence. That’s also very depressing and doesn’t bode well for us.

(There’s also “they’re out there and they’ve found something so scary they have to hide.” I don’t like that either.) Yes, There Have Been Aliens