Well, maybe. It's a worthy goal in the sense that eliminating disease would be great. But they may just end up blowing a lot of money that could have been spent more profitably on reasonably attainable goals.
The first emperor of China spent a nontrivial amount of his country's economic output trying to find the secret of immortality. Would that have been a good thing to learn? Certainly. Was it worth trying? No.
While your example seems fitting at first glance, I don't really think it's relevant. This is private money spent on something that may be a public good, and in this case we do have a basis for saying that, yes, we can eradicate diseases, we've done it before and we're getting close again with others.
All I'm saying is you can end up wasting a lot of money by stretching for a goal that's too far ahead of current technology, and in that sense it might be a more efficient use of money to attempt something more near-term.
1. We don't understand the consequences of this.
2. Our notion of disease has changed (as a previous poster noted, think about our thoughts on homosexuality)
3. Technics used to address disease have historically had some severe unintended consequences (e.g., antimicrobial resistance)