Mariusz, you might be surprised how many people are big fans of both groups. Two of my all-time favorite concert memories are Deep Purple at Olympia Stadium (although it was actually an arena) and when a friend of mine got me a front-row seat for Roger Waters at Little Caesars Arena a few years back.
Like I say to my friends when discussing politics or religion - hey, can't we all just get along?
p.s..the Deep Purple show was within 2 days of Aerosmith at Cobo Hall, and my hearing hasn't been the same since.