I agree with both of you. December is always calm and first days of January always bring decrease - hopefully this time not big, and in the middle of January price will jump over $400, but it still is optimistic scenario imo
For general stock market, the December is a good season. The prices usually rise. That is mainly due to year end effect. Fund managers sell bad performing stock and buy good performing stock to do some window dressing. These fund managers do not care about the cost involved in the buy/selling process, they just want to show investors that they have the winning stock.