We're hoping for _a_ treatment to work. Trump's motivations were largely self-interest, financial investments and other.
We didn't celebrate because Trump was wrong. There was skepticism about the treatment, but he (not a physician) was up there pimping it. Even he didn't necessarily believe it was the cure. For all he said that, he said "Hey, take it anyway, why not? Can't hurt!" (when indeed it can). Finally came conclusive evidence that "You are wrong. Be quiet." Though Trump being Trump, that didn't overly work.
It's no different to "Pharma Bro" Martin Shkreli, who once lodged an appeal / protest against a drug being approved...
Not because it was dangerous. Or less effective. Or more expensive.
No, in fact it was safer than treatments out there. And more effective. And cheaper.
And all those reasons meant he opposed it. Because it wasn't _his_ drug. People who say "Big Pharma is holding the cure to cancer", etc., all those conspiracy theories? Shkreli literally opposed a better drug because it would cost him and his company profits.