The most coveted ticket in all of South Korea right now is the one that will get a fan of BTS into the K-pop band's show Saturday in the southeastern port city of Busan, a happening likely to be the country's biggest sensation of the year. But it's what happens next that matters most.

The concert - before some 50,000 deliriously excited followers of the boy-supergroup - is no ordinary performance. It's the heart of a $5 million marketing push in pursuit of a near-obsession for both Busan and the national government: hosting the World Expo in 2030.

South Korea is going all out. Busan, its second-largest city, has even asked the government to spare all seven BTS members from mandatory military service so they can be the face of the Expo bid. Huge business conglomerates are financing massive advertisement campaigns to promote it.

The nation's leaders have pushed for years for South Korea to become the seventh country in the world to host all three global mega-events, which they believe is key to raising its global profile and building soft power. They snagged the soccer World Cup in 2002, and the Olympics in the summer of 1988 and the winter of 2018. The World Expo, held for six months every five years, would be the final prize.

Yet their sales pitch has faced challenges. The concert has wrought logistical nightmares for the city, and polls show its 3.4 million residents are lukewarm on the effort.

So why does Busan want the expo so much?

The event began in 1851 as a celebration of cultures and innovations from around the world. For emerging societies, it symbolizes their arrival in the top rank of nations, said Nicholas J. Cull, a public diplomacy expert at the University of Southern California. For those with more established reputations, it can serve as a reminder of their stature.

South Korea is closer to that second category. It is the world's 10th-largest economy, and Busan is a popular convention city and home to the Busan International Film Festival - a premier gathering in Asia.

In many ways, Cull said, the country is past the need to put itself on the map with the Busan World Expo. And image, he added, is not just about selling positive attributes but also about eliminating the negative elements that can undermine global standing. One of those is South Korea's growing income inequality, which has inspired internationally recognized movies and TV shows such as "Parasite" and "Squid Game."

"I think that South Korea is beyond the need for a coming-out party. The Seoul Olympics served that role. It is increasingly in the category of a country from whom great things are expected," Cull said. "Many South Koreans are concerned about problems in the country and want to ease those negatives first, even if they are splendid themes for hit movies and TV series."

Still, city and national leaders say the 2030 World Expo would be a financial and reputational boon. Its bid committee estimates total spending at $3.4 billion, while the economic benefit generated directly and indirectly by the event is projected at $42.7 billion, according to analysis by a government-affiliated think tank.

The tourism industry is critical to Busan, where service jobs account for about three-fourths of all industries, said Lee Sang-ho, professor of tourism policy and cultural tourism at the Pusan National University in the city.

"I am sure that the charm of Busan - and the value of its tourism resources - will gain much attention. Above all, I think it will be an opportunity for Busan citizens, who tend to be conservative, to interact with tourists from all over the world, which is difficult to quantify in economic value," Lee said.

The city's competitors for the host spot: Rome, Riyadh and the Ukrainian city of Odessa.

One undercurrent of concern stems from these expos' mixed record. The 2020 event in Dubai led to about $38 billion in government-related debt, according to a forecast by London-based research firm Capital Economics. James Swanston, a Middle East and North Africa economist at the firm, noted many factors, including the Dubai government's lofty targets for tourist arrivals and the number of expo visitors who would eventually become residents there.

And in Osaka, Japan, which will host in 2025, there are worries about skyrocketing construction costs sparked by global supply chain shortages, a weakened yen and inflation. Fewer countries plan to participate than initially anticipated. Businesses are questioning whether they will recoup their investments, according to Japanese news outlet Jiji Press.

In South Korea, the main controversy surrounding the Expo push is the Busan mayor's proposal for the members of BTS to "serve the nation in their unique capacity" and waive their mandatory enlistment - a highly controversial privilege that until now was largely reserved for top athletes and classical artists who help "elevate national prestige."

Under a conscription system established to counter threats from North Korea, the country requires all able-bodied men to serve at least 18 months in the armed forces by age 28, though the parliament revised a law in 2020 to let K-pop stars postpone their service until they are 30. (The two Koreas are technically still at war given the absence of a formal peace treaty following their 1950-1953 conflict.)

Culture Minister Park Bo-gyoon, whose predecessor had told reporters that it would be "a cultural loss for mankind" should BTS stop performing because of military conscription, said last week that the ministry will "confirm our stance as soon as possible." Vocalist Kim Seok-jin, who goes by Jin, faces a December enlistment deadline. The 29-year-old is the band's oldest member.

The proposal has split public opinion and triggered a broader debate about social justice. Political analysts and legal experts say it would set a harmful precedent.

"Exemptions are exceptions, and exceptions should stay minimal," said Shin Hee-Seok, a legal researcher at Yonsei University in Seoul. "Setting a precedent for BTS could open a floodgate of applications from the K-pop industry. I don't think the government would want to handle that."

The Grammy-nominated group, which has sold tens of millions of albums since its debut in 2013, went on hiatus in June as some members awaited enlistment and others pursued solo projects. Saturday's concert will be their first performance since the break, and so it has drawn even more attention from the massive fan base known as the BTS Army.

Because Busan is not paying for the show, the band's parent company and other South Korean businesses are financing it. Companies such as cellular service providers, the Korean conglomerate Lotte and others raffled off concert tickets for customers who bought their items - including cellphones, chewing gum, hamburgers and Krispy Kreme doughnuts. All tickets have been snatched up.

Lee reported from Tokyo, Kim and Li from Seoul. Julia Mio Inuma in Tokyo contributed reporting.