I don't think it's hard at all, so long as you leave in a reasonable and respectful way. I'm in technology (a large software company, so Microsoft and Apple are not bad analogues for me) and it is definitely musical chairs. Some guy starts at EMC, goes to NetApp for more money, goes back to EMC as a manager etc etc. I knew a guy who started as an inside sales rep at my (large software) company, he got promoted to a field sales position and they shafted him on the raise. He then went to a large storage manufacturer and has since come back in a specialist sales role for much more money than he would have been able to get if he stayed.
So as long as you treat your company well and don't burn any bridges, maybe keep a few relationships going over time, I think it should be easy. In some industries it is standard practice.