> having had the flu a couple times in my life I know that it sucks but it's still only a couple of days of misery

Because you've been lucky. The flu can and does kill healthy young people. I cannot understand why you would value your anecdotal experiences above population studies and your own life. Anecdotally, I've had friends my age and healthier than me end up in the hospital with pneumonia after getting the flu. A classmate of mine died from H1N1 when I was in middle school. Even if I didn't have those experiences, why would I not take such a simple action with basically no risk to protect myself from a very real threat?