I would guess that a) spending rapidly reaches the point of diminishing returns and b) it's probably very, very hard to effectively target research money. As such, it might simply not be effective to spend more.
In addition, he'll probably continue investing in research going forward; $50M to date might eventually increase depending on what's found.
In addition, he'll probably continue investing in research going forward; $50M to date might eventually increase depending on what's found.