Matthew 27

I have a problem with this.
It just doesn't make sense to me.

Mat 27:6 And the chief priests took the silver pieces, and said,
It is not lawful to put them into the treasury,
because it is the price of blood.
Mat 27:7 And they took counsel and bought the potter's field with them,
to bury strangers in.
Mat 27:8 Therefore that field was called, The Field of Blood, to this day.
Mat 27:9 Then that which was spoken by Jeremiah the prophet was fulfilled,
saying, "And they took the thirty pieces of silver,
the price of Him who had been priced,
whom they of the children of Israel valued,
Mat 27:10 and gave them for the potter's field,
as the Lord appointed me."

If we can assume the cheif priests were familiar with their own holy scripture,
wouldn't they know
that the only place in the entire Old Testament that "thirty pieces of silver" are discussed
is in a prophecy that directly ties them to a potter?

I searched, and here is the ONLY reference:

Zec 11:12 And I said to them, If it is good, give My price; and if not, let it go.
So they weighed My price thirty pieces of silver.
Zec 11:13 And Jehovah said to me, Throw it to the potter,
the magnificent price at which I was valued by them.
And I took the thirty pieces of silver
and threw them to the potter in the house of Jehovah.

So my question is, knowing the scripture,
Wouldn't you be an idiot to take Judas' money and go buy a potter's field with it?
thereby fulfilling the scripture?

Wouldn't you rather buy just about anything else,
just to keep this Jesus character from becoming validated by the prophets?

Wouldn't you try to avoid having this event be forever tied to Old Testament prophecy?

I don't get it...

What were they thinking?

I also tried to get some insight from the commentaries I have,
but all of them are obsessed with discussing the fact that the prophecy appears in Zecariah instead of Jeremiah,
and offer various explanations for the apparent discrepancy in verse 27:9,

but none of them discuss the actual event!
lame...