Because, science, Bitches!
I found the original article, but it's in German.
I seriously doubt this story is true, scientists are not into causing death/disability, and they only have to find a few of the many church-sponsored Covid Parties to do this.....
Furthermore, Googling the source "IFL Science" says it is a comedy site.
I Fucking Love Science is a Facebook group, and yes, they share lots of humorous science themed memes, but also legit science. As I said, I found the original article, and yes, it is true, though I suspect you didn't even read the one in the link I posted or you would see that they are doing this solely as a research study.
"The volunteers, healthy people aged 18 to 50, will be tested for Covid-19 48 hours before the concert and they will only be allowed to enter if they test negative. The researchers will give the concert-goers an FFP2 filter face mask and a fluorescent hand sanitizer that allows the scientists to track the surfaces most often touched by audience members."
That's what science is, controlled experimentation.