I think the flip side can also be said. There might be a possibility of good or bad happening in the unknown, but it's still unknown. Known is predictable, safe, and comfortable. Unknown is unpredictable, potentially unsafe, and uncomfortable. Could the unknown be good? Sure, but no amount of good can change the fact that it's unknown. It's not necessarily about gambling either or not the unknown is good or bad, sometimes it's more of just whether or not to let the unknown in or not.
Would you consider yourself an anxious person?