Whether or not you like the idea (as someone who dealt with the $£€ marathonphoto in order a moment for my first 'thon, I personally think it's great), people are really overestimating the data cost.
You can get 1 TB from Google drive for $10/month (10 TB for $100), which will hold between 500k and 2 million photos, depending on quality. 1.5 million spectators likely won't upload 2 million photos. Leave them up for a month and delete them.
People always make the 'better quality' argument, but it doesn't stop people from illegally streaming low resolution sporting events/films. Remember how long blueray lasted?