The Turkish agreement is meaningless - if all of Europe had been vehemently opposed to importing immigrants, immigration would have stopped at the Turkish-Syrian border. Immigration did not happen because of the Syrian war - it was a constant trend. What opened the spigot was the fall of hard regimes in North Africa such as Libya, Tunisia and North Africa (something EU biggies like France, Netherlands, Germany supported because "dictators bad!"), which led to their own borders becoming much weakened.
Third, no immigrant wants to settle in Hungary because they're immigrants, not refugees. And as immigrants, they're simply choosing the country with the best welfare. There was even an article in 2016ish I read (I'm sure there are loads) where an interviewee said that he was taking his family from Greece all the way to Sweden because the welfare benefits were better.
Additionally many blame the likes of Merkel for the self righteous stance unaware of the fact that she (and her Dutch partners and such) had the greatest effect on building down inflow with an agreement she started brokering with turkey well before her famous comment. On the other hand fences and hard rhetoric in Hungary or the like did not visibly affect the numbers of incoming refugees.