WHy does it seem like timing the market isn't that hard?

This is the test I did. I took a month predicting the way the market(NASDAQ) went on days I was certain of the result. Of the 10 days I guessed, 9 were correct. I didn't force a guess I days I wasn't certain. I didn't use complicated math modeling or anything like that. So I don't think I am some kind of genius. My question for this group is how is this possible if timing the market is so difficult?

I would bet my results would be far worse on individual stocks.