Event planner Andy King is disappointed in Billy McFarland -- saying he hoped prison would've knocked some sense into him after the first Fyre Fest fiasco, but clearly not ... 'cause round two is already going up in flames.

In a lengthy IG post, Andy said he was all for giving Billy a second chance -- standing by him when no one else would ... even linking up with him a year and a half ago to help him focus on empathy and paying back people from the OG festival. But clearly, it was all for nothing.

Andy added that on top of losing hundreds of thousands of dollars of his own money, his career also took a hit -- getting labeled as toxic for his ties to the infamous fraudster.

In fact, Andy says that when they started discussing a financial package to make sure he got paid this time around with FF2, Billy straight-up ghosted him and went off to do his own thing.

Andy shared a post with a screenshot of himself from the 2019 Netflix doc "Fyre: The Greatest Party That Never Happened" -- something he says he did for free just to help tell the real story and set up a GoFundMe to pay back as many people as possible.

His post pretty much summed up his belief that Billy never shared the same goals -- saying he’s genuinely saddened by Billy’s actions and, from the looks of it, he's setting himself up for another failure.

TMZ obtained text messages from a Fyre Fest 2.0 event producer saying the May event is blaming the Mexican government for pulling the plug on the event in Playa del Carmen.

According to the producer, officials are acting like they had no clue the fest was even happening -- a wild twist, considering Billy claimed just a day earlier that his team was working with Playa del Carmen to move things forward, even posting a whole timeline of supposed interactions.