Yeah, I agree God know's what's going to happen...but that is not saying that he didn't give us choice in the matter...Pharaoh was given chance after chance and saw many signs and wanders, yet he chose to harden his own heart, and that was before God chose to make it even harder...Pharaoh became a reprobate of his own doings....He did not like to retain God in his heart and God gave him over to a reprobate heart to do those things which were not convenient... and yes, God did then make an example of him, and he was not the only one that did this and God made an example of...I think that is why it also says today if you will hear his voice harden not your hearts. God gives us all a chance, but if we harden our hearts and continue to do so then we can and will become reprobates...but that is on us...
I think this is our warning not to harden our own hearts...
Hebrews 3
7 Wherefore (as the Holy Ghost saith, To day if ye will hear his voice,
8 Harden not your hearts, as in the provocation, in the day of temptation in the wilderness:
9 When your fathers tempted me, proved me, and saw my works forty years.
10 Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.
11 So I sware in my wrath, They shall not enter into my rest.)
12 Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God.