For all we know the galaxy may be rife with technologically advanced civilisations.
This argument is only taking into account "technically advanced civilisations" in the context of our understanding. This effectively bypasses one of the objections to the Fermi paradox - saying that the galaxy is not rife with technolgically advanced life is a little misleading, there are in fact many objections to the Fermi paradox and I personally believe that resources is one of the least valid objections. Essentially once any sufficiently advanced civilisation achieved non planetary manufacturing facilities resource objections become less valid - although Chalnoth I must grant that I think in the early phases
To assume in the meagre time we have been actively looking via SETI would produce results does seem a little naive on humanitys part - assuming the size of the galaxy.