Are you also happy about the millions who died during WW2? Darfur? Rwanda? Congo? Russia? China? Etc, etc,etc.
Maybe the suggestion of "happiness" refers to the ending of several years of being imprisoned in a virtually nonfunctional body. Everyone dies. Some die quickly, with little suffering and some don't. Being trapped in a totally dependent state, requiring others to perform normal life functions for a period of several years is severe torture at best. It seems morbid to require this to continue on the slight chance the condition might change.
As you pointed out, there are many other deaths which we would do well to help prevent.