[csense]

The more philanthropy or private investment we can attract to scientific innovation, the better.

The public gets the benefit of inventions that wouldn't have existed without this investment (assuming they're marketed in the short term, and in the long term the patents eventually fall into the public domain).

Or alternatively, if billionaires start doing more research, this could be offset by cutting, or slowing the growth of, taxpayer-funded research spending. And give the money back to taxpayers in the form of tax cuts, deferred tax hikes, or different services.

Also, there's less of the waste and uncertainty associated with government spending (think about how many articles you see on long-running science experiments disrupted by Washington's latest budget spasm; if Gates has dumped $100 million into AIDS research and needs $100 million more to produce a vaccine, he's probably going to follow through).

And if things go awry the fallout's not as bad (if Solyndra had happened to some billionaire spending his own money, I don't think anyone would have been outraged).