Because otherwise you would not know that you have a deadly disease. And the argument that 10.000 people may have it while the person 10.001 will instantly drop dead from it is insane and bullshit. That is pure insanity.
That sociopath study is pure bollocks - not only was it based on questions like: 'Will you use hanitizers every chance you have during the day?'. Then they did not even connect to any reason for the people who refused to wear masks. Their logic went following:
'You know that wearing face diapers, dousing yourself in cancer-causing-eyesight-destroying hand sanitizer saves lives, but you refuse to adhere to those rules becuase you don't care about grandma dying.' It's not that some people including leading doctors disagree with the preamble.
Seriously it's literally back to communist psychiatric arrests of dissenters: 'You must be crazy for not believing this USSR to be a the best utopia on earth! He must be crazy because there is no other explanation!' Because there could be no other explanation for not putting on an ineffective face diaper but the willing desire to kill grandma.