Well, as I understand it, it's as follows: (i) There's abundant genetic evidence that all American Indians are descended from a group that was in Eastern Siberia circa the Clovis migration, and no evidence of any descent from any earlier groups. (ii) There are Clovis and Folsom points everywhere, so they spread quickly over the entire hemisphere, and it's not clear why a pre-Clovis culture wouldn't have spread equally quickly. What I find particularly odd is that it seems many of the South American Clovis-descended groups have been isolated since they settled the area, so why were there no pre-Clovis refugia in the Amazon? (iii) A perfect archaeological site would have several layers that indicate settlement over a long period of time or at different periods, and the evidence that pre-Clovis sites were continuously settled is always much more dubious (like, bits of charcoal) than the dating of the stone tool. (iv) To get from Siberia to Oregon on foot, you need Beringia above water and the Mackenzie pass open, but because the pass opens during interglacial periods and the Bering Straits disappear during glacial periods the pre-Clovis timing is tricky. You could also sail from Siberia to Oregon, and this would explain why there is so little evidence of a wave of pre-Clovis migration spreading out, but there is absolutely no evidence for this (and there isn't even direct evidence that any humans had boats before 8000bc). (v) People are always proposing even wackier ideas than the boats for how the pre-Clovis people got there, like European settlers or migration circa 50,000 bc, for which the evidence is much worse than the pre-Clovis sites themselves.
Maybe you're an archaeologist or something and know all this but find the specific conclusions of people in your field irritating and obstinate... but if you only have a passing familiarity with the issue, the answer is the problems with the pre-Clovis theory are serious. Can you discard the possibility that there is some sort of error with the datings before archaeologists settle on firm answers to those questions?