you want to avoid a bogey because it starts a vicious cycle. assuming you are at par, a bogey requires a birdie just to get back to par. going for that birdie risks another bogie that would require another birdie to balance, and so on. playing in this highly volatile manner you run a higher risk of having to make great shots in order to end up with an average score. it's more in your favor to wait until you make a great shot (say a great second shot on a par 4 that leaves you two feet from the hole) and then capitalize on the "free" consequence (the two foot birdie putt) that actually takes you above average than to be forced to sink a 50 foot birdie just to stay at average (because you missed par on the previous hole).