Why didn't Dumbledore attend the Quidditch World Cup final?

Question

Britain hasn't hosted the Quidditch World Cup for 30 years and a hundred thousand wizards & witches will be coming to Britain to watch it. So security should be an important factor for the organisers.

I do hope you will allow us to take Harry to the match, as this really is a once-in-a-lifetime opportunity; Britain hasn’t hosted the cup for thirty years, and tickets are extremely hard to come by.

&

“It’s been a massive organisational problem,” sighed Mr. Weasley. “The trouble is, about a hundred thousand wizards turn up at the World Cup

Now Dumbledore is your best wizard who can manage everything that you ask for, let alone security. His mere presence means that nobody would dare to make trouble. So yeah the question arise, why wasn't Dumbledore present in the Quidditch World Cup Final?

Answer 1

Because the Ministry wasn't expecting any issues with Dark Magic.

It's true that Dumbledore's presence scares Dark wizards and witches. Even Lord Voldemort feared him. But the Ministry is a government with its own branch of people in charge of policing. It isn't really feasible to have 'bring Dumbledore along' as their default position whenever they need to think about security. It's kind of humiliating and Dumbledore isn't necessarily going to make himself available whenever the Ministry might wish him to appear.

Besides, the Ministry wasn't anticipating trouble of that sort. When the Death Eaters began marching through the campsite and the Dark Mark was set off it took them completely by surprise. It's true that there were significant precautions in place. But these were precautions to guard against Muggles, not Dark wizards.

"Been having a lot of trouble with [Mr Roberts, a Muggle]. Needs a Memory Charm ten times a day to keep him happy. And Ludo Bagman's not helping. Trotting around talking about Bludgers and Quaffles at the top of his voice, not a worry about anti-Muggle security."
_{(Goblet of Fire, Chapter 7, Bagman and Crouch).}

This focus was reflected in the spells that were cast on the stadium.

"Ministry task force of five hundred have been working on it all year. Muggle-Repelling Charms on every inch of it. Every time Muggles have got anywhere near here all year, they've suddenly remembered urgent appointments and had to dash away again...Bless them," he added fondly...
_{(Goblet of Fire, Chapter 8, The Quidditch World Cup).}

Even Voldemort was aware of why the Ministry was being so paranoid.

"Because, fool, at this very moment wizards are pouring into the country from all over the world, and every meddler from the Ministry of Magic will be on duty, on the watch for signs of unusual activity, checking and double-checking identities. They will be obsessed with security, lest the Muggles notice anything. So we wait."
_{(Goblet of Fire, Chapter 1, The Riddle House).}

So the Ministry wouldn't have reckoned that it needed Dumbledore's help. It didn't think that an attack by Dark wizards was likely. They probably didn't think it was possible. Voldemort was gone and his followers were believed to have been rounded up and sent to jail.

What they were really worried about was a mass leak to the Muggles. Dumbledore wouldn't have been much help to them with this kind of security. They can do Muggle-Repelling Charms without his help. So it's not at all likely that Dumbledore would've been invited to come to the Quidditch World Cup for security reasons.

It's also doubtful that Dumbledore would've wanted to attend himself. He was pretty bookish and I don't remember him expressing much enthusiasm for watching Quidditch in the books.

Answer 2

Dumbledore was busy with the Triwizard Tournament

The Quidditch World Cup Final wasn't the only big thing happening that year. The Triwizard Tournament was also taking place in Hogwarts. It may not have been so obvious in the movies, but the Tournament was a big deal. The Ministry of Magic itself had a part in planning the Tournament.

The safety of his students is an important charge for a headmaster. The Tournament was importing highly dangerous creatures, and Dumbledore had to take the necessary precautions to protect his - and Beauxbatons's and Durmstrang's - students.

“Oh, and I almost forgot,” Fudge had added. “We’re importing three foreign dragons and a sphinx for the Triwizard Tournament, quite routine, but the Department for the Regulation and Control of Magical Creatures tells me that it’s down in the rule book that we have to notify you if we’re bringing highly dangerous creatures into the country.”

The Tournament had not been held for a century, meaning that extra precaution had to be taken to ensure the safety standards were met.

“As I was saying,” he said, smiling at the sea of students before him, all of whom were still gazing transfixed at Mad-Eye Moody, “we are to have the honor of hosting a very exciting event over the coming months, an event that has not been held for over a century. It is my very great pleasure to inform you that the Triwizard Tournament will be taking place at Hogwarts this year.”

“There have been several attempts over the centuries to reinstate the tournament,” Dumbledore continued, “none of which has been very successful. However, our own departments of International Magical Cooperation and Magical Games and Sports have decided the time is ripe for another attempt. We have worked hard over the summer to ensure that this time, no champion will find himself or herself in mortal danger.

Dumbledore had the Tournament to worry about, and Voldemort's Horcruxes as well. He had his hands filled, and therefore had no time to attend the Quidditch World Cup Final.

Given the choice between planning the Tournament's challenges in a way that ensured safety for his students and serving as a "wizard-bodyguard" whilst attending the Cup, he obviously chose to ensure the safety of his students, given that there was already a high-level of security there: comprised of many Ministry wizards and the Minister of Magic himself.

And also, it's probable that Dumbledore didn't even get tickets in the first place.

“I do hope you will allow us to take Harry to the match, as this really is a once-in-a-lifetime opportunity; Britain hasn’t hosted the cup for thirty years, and tickets are extremely hard to come by.”