What's the worry? "Sea level continues to rise at a rate of about one-eighth of an inch per year" -- NOAA?

Because that rate has more than doubled in the past few decades, and the current rate appears to be even higher than that. There are good reasons to believe it will keep increasing.

There is a limited amount of water in the world. In fact, all the water in the world is pretty much the same amount of water as there has always been. The only water available to increase the 'depth' of the oceans is frozen and THAT, given the vast expanse of the Earth's oceans is VERY small. Make an ice cube out of a bath tub full of water. Throw it back into the bath tub. The affect is immeasurable.

At most, sea levels will rise a TOTAL of two or three inches. If that's enough to cause a crisis for you in 20 to 50 years? Deal with it. 

erosion. sht falls in the water. Not to mention the number of supertankers, cruise ships and naval vessels displacing trillions of gallons of water. Then you got underwater volcanos and seabed rise.

We don't care, just move to higher ground or build a wall.

Even minuscule amounts of sea level rise can have devastating impacts on the planet.

The oceans are MASSIVE so even 1/8 of an inch is substantial.

And yet, there is no proof of that, only a small percentage of a possibility.

I thought it was 3 inches a year..