"Happy holidays" makes sense when a company does it or asks employees to say it: Christmas may be the most marketable and the most celebrated, but you want to treat all of your customers right, right? I'm more bothered by people's incessant bitching about it than the actual thing. People will say what they want to say, and they have every right. Douchenuggets who insist on hearing 'merry christmas' and make a scene about it really mess with the spirit of the season, kind of bring me down. And you never seem to hear people making the same fuss about lack of accommodations for other holidays. People who celebrate christmas have been spoiled, and don't like the change. It has nothing to do with their beliefs being infringed upon.
TL;DR: If you really need to hear someone say "merry christmas" then go to a church.