I'd think the conclusion you should draw is not that "even the famous experiments were not valid, so nothing in psychology is" but rather "the validity of an experiment does not correlate with how famous it is".
A direct conclusion. The insight I'll draw from that is that academia gives voice to the results the current zeitgeist finds interesting and believable without properly verifying the evidence.
See also the replication crisis.
I guess my point is that I don't need to think for long before I find an example justifying why physics is a serious field.
What would be the equivalent of Newton's laws in psychology? Does such a thing exist? Or does the whole field just prove how complicated human beings are by being incapable of proving anything else (which in itself would be an interesting result, don't get me wrong)?