You're welcome. The condition you describe is called "moneyball-itis" -- or "next-to-moneyball-itis."
What you can do -- and is actually easy to do if you can program this as a habit -- is instead of letting your attention divert towards the 8-ball as you get closer to it -- divert your attention to one of your opponent's balls nearest to the 8-ball.
In other words, don't do the "OMG! I'm getting close to the 8-ball and winning the game! OMG!" attention-grabber. Make believe you have one more ball beyond the 8-ball. This will take the "golden aura" away from the 8-ball so that you're not sharked by it.
Yes, when shooting your last ball of your category prior to the 8-ball, you may already be a victim of moneyball-itis, because you're obviously trying to get position on the 8-ball, in amongst the rest of the congestion on the table. Your attention is being diverted away from making that penultimate ball, so that you can get position on the 8-ball, and TOO MUCH attention has been diverted, so you end up missing that penultimate ball (perhaps you "threw your stick at it," or you took it for granted?). Instead, think of the 8-ball as your "next to last" ball, as if you're trying to get position on something else beyond the 8-ball.
Try that for a few games, and see if it takes the "aura" away from the 8-ball. It should force you to put more attention on the "make" for that penultimate ball.
Hope this helps!
-Sean