Be skeptical, that’s okay. Polling is never exact. It is good at giving you trends, and right now, the trends are not good. As someone from Wisconsin, I’ve seen firsthand that running a weak candidate and assuming they will do well can cost you the election. Ron Johnson has literally spent a July 4th in Moscow, he had fake electorates in hands ready to over turn the election. Mandela Barnes initially polled well against him, but his numbers degraded because he ran such a weak campaign. Barnes lost that election, yet we voted for the democratic governor. Barnes was such a weak candidate that enough people voted a split ticket to re-elect Johnson.
The point of the story is don’t just stick your head in the sand and make up excuses about polls.
Edit: Also 40% is 1465, which is a good sample size.