This is not about the waste of water. This is not about ALS being an orphan disease that needs attention. This is about what the public can do about science funding.
The amount raised is non-trivial, over $100 million (1 x 10 ^8) by last count, three times the NIH allocation. The NIH budget is on the order of $30 billion (3 x 10 ^10). The amount raised is more than the NIH budget for ALS.
Are there 100 diseases that are as important/severe/deserving of our attention as ALS? Depends on what your mother is dying from, how uncomfortable the old prostate glands sitting in Congress are, whether your beloved is HIV positive, or you have friends in West Africa right now. Are there more than 100 conditions/situations/problems that NIH addresses, I would guess yes. How does one decide what is important?
The Libertarians would argue this is better than NIH, as people are choosing where their money goes. And people should be able to chose where the money goes.
But what if all those people who donated took the time to write their Congresscritter (or leadership in other countries, which are worse at funding scientific research than the US, afaik)? What if all those people took the somewhat less sexy/viral/interesting route to do something to promote spending for research?
So I see two problems here. First, how do we decide what gets funded? I'd argue that right now NIH is going through a spasm of short-sightedness wanting things that produce results right now. The second, how do we get people interested not in just the short-term/sexy/popular causes, but to do more to change the resources for research?