There was one time, when Turkey had a legitimate chance of joining the EU, back in 2005ish. Back then, one of their biggest supporters of their EU candidacy was Greece. Greece wanted to normalize the relation with Turkey and Turkey wanted to become a normal european country. Greece was even willing to throw Cyprus under the bus, by supporting the Annan Plan, which was objectively terrible for Cyprus. Though the thinking was "if Turkey becomes "normal", then any negative part of the deal wouldnt be relevant, it could be like Belgium". Though Cyprus(and pretty much all its political parties) voted against the deal.

Erdogan was seen as the extrovert, moderate muslim, someone who could merge moderate Islam with european values.

Nowadays, Erdogan and Turkey are on a completely different place. Erdogan has said "we might come on night" and "our missiles can reach Athens".

https://www.politico.eu/article/recep-erdogan-turkey-threat-against-greece-g20/

https://www.politico.eu/article/erdogan-warns-greece-that-turkish-missiles-can-reach-athens%EF%BF%BC/

Turkey is constantly pushing their "blue homeland" concept, which basically includes a lot of greek islands in the Aegean. And thats on top of ridiculous Exclusive Economic Zone(EEZ) claims that basically say "(greek) islands have no EEZ rights". Turkey feels that it has been historically wrong and that they need more "breathing space" in the Aegean sea(where Greece owns all the islands except 3).

And even the turkish society is different. There is a greater chasm between western/urban Turkey and the rest of Turkey. There was a hope that the rest of Turkey could slowly transition closer to european values, but nowadays it seems the country is getting split in half and each half is moving further away from the other.

And last but not least, the russian invasion of Ukraine has shown to the world that integration and shared economic interests do not always translate to peace. So do we really want to do the same mistake with Turkey?

PS I am greek, so i am biased.