1 Cor 10:13 NIV: “No temptation has seized you except what is common to man. And God is faithful; He will not let you be tempted beyond what you can bear. But when you are tempted, He will also provide a way out so that you can stand up under it.”
Either you believe the Bible or you don’t. Sometimes I wish I could edit the Word, but He provides a way out of that temptation also.
“What is common to man” is a relative term, it's the difference of being tempted by Heidi Klume or Hellen Thomas. One evokes a much more potent response than the other. The power of drugs is no different, resisting pot is much easier than crystal meth once you've made the mistake of going down that path.
At what point does God no longer protect us from our own poor choices? I don't believe he does it continuously only in the beginning. But I also believe once we've made that “slide to the bottom” he offers a hand to lift us out.
It's the training of children, they will make mistakes and they must learn from them by enduring their own self inflicted pains. Once the lesson is over the parent helps the child recover and often times has the child reflect on their mistakes to avoid the same in the future.