It does not say "the prince of the people", so why are you acting as if it does? It says "the people of the prince that shall come". The prince that shall come had previously been identified as Messiah the prince and He came exactly when the prophecy said He would right after the end of the 69th week and then He was cut off in the midst of the 70th week and He confirmed the new covenant at that time and made the old covenant sacrifices and offerings obsolete.
Daniel 9:26 And after threescore and two weeks shall Messiah be cut off, but not for himself: and the people of the prince that shall come shall destroy the city and the sanctuary; and the end thereof shall be with a flood, and unto the end of the war desolations are determined.
Can you see that this doesn't say "the prince of the people that shall come"? Please stop quoting it as if it does.
What you seem to be overlooking is what the text says and actually means in relation to when it is actually fulfilled in real time.
and the people of the prince that shall come shall destroy the city and the sanctuary
Daniel 9:26 says---and the people of the prince that shall come shall destroy the city and the sanctuary.
Regardless of whether you understand this as referring to 70 AD or to a future event, the sequence matters.
If this refers to 70 AD, then the Messiah had already come, completed His earthly ministry, been cut off, risen, and ascended. Yet the text does not say the prince who came or the prince who had come. It says the prince that shall come, and it is his people who destroy the city and the sanctuary.
Historically, who destroyed Jerusalem and the temple? The Romans.
If you identify the coming prince as Christ, then the Romans become the people of Christ in this passage. But that seems difficult to reconcile with the NT's ordinary use of Christ's people. For example, John 1:11 says----He came unto his own, and his own received him not.
That is speaking of Israel, not the Romans. The Romans are never described as Christ's people in the sense Daniel 9:26 would seem to require if Christ is the prince whose people destroy the city.
There is also a consistency issue with your broader eschatology.
You reject the preterist interpretation of Matthew 24:30 because you understand Christ's coming there to refer to His future second coming at the end of the age, not His coming in judgment through the Roman armies in 70 AD.
Yet if Daniel 9:26 identifies Christ as the prince that shall come whose people destroy Jerusalem, then the passage naturally lends itself to the very idea that Christ came in judgment against Jerusalem through the Romans in 70 AD---the same basic framework Preterists use in Matthew 24.
So there seems to be a tension in your position. On the one hand, you reject Christ coming in judgment through the Romans in Matthew 24:30. On the other hand, your reading of Daniel 9:26 appears to require Christ to be the prince associated with the Roman destruction of Jerusalem.
How do you reconcile those two positions without applying two different standards to two passages?