I never got why people have to move over 500 miles to relax. Is it really that difficult to relax at home?

This may be a confusion over the meaning of 'relax'. I find a vacation away from home more energizing than one spent at home partly due to the 'a change is as good as a rest' phenomenon.

I think for me being removed from environmental cues that are associated with the stresses of day to day life is also helpful. I found climbing a mountain on my vacation last year more 'relaxing' in this sense than spending the same amount of time sitting around my apartment despite it being physically taxing for example. I also find myself more relaxed/replenished if I've gone snowboarding on a Sunday than if I've sat around my apartment all day watching TV.

This may be a 'personality type' thing.