So you're going to sell your surfboard and buy new ski equipment every winter, and sell your skis and buy a new surfboard every summer? As well as the rest of your bulky seasonal gear?
I think you're ignoring the point that if you want high-quality gear, it's cheaper to buy it outright and store it off-season.
And the kinds of people who live in places where they don't have room to store a surfboard year-round, are the kinds of people who don't have a bunch of wall space for one either.
I think you might not be totally understanding the concept of small urban apartments. Putting skis in the closet or under the bed year-round doesn't work, because your closet and underneath the bed are already full. (And it's not just skis, obviously -- it's boots and poles and helmet and bulky jacket and snowpants and gloves and everything.)
You can rent skis for a season for $400, I suspect most rental places are than $100/month.
But skis especially can usually fit in the back of a closet or under a bed.
Kayak? Get a season pass for the rental place.