In so far, more people have died from this stuff and his hyping it up than I am aware of ever being helped by it in any capacity. This feels like a panicked group of people trying to throw anything they can at the wall.
In terms of risks, using this Malaria drug on COVID patients probably carries the same risks as your usual prescription drugs. You probably won't die from it but you do have to be mindful of the side effects, which can be severe in some cases. But I think the biggest issue I see is if there's a mad dash to purchase this drug and it ends up just being a placebo, and then the people who actually need the drug for its intended purpose can't get a hold of it.
Trump constantly looks for 24-72 hour solutions. He's willing to roll the dice and take whatever risk if it can get him through the current news cycle. If there's any fallout from current decisions, he'll just say or do whatever to get him through the next news cycle and repeat. Just a stream of short-term bandaids and bluster. With our current media environment and the short attention span of the public, Trump has been able to get away with it for the most part. Like his "Easter Opening Day" nonsense. It got him through the news cycle and boosted the markets a bit and now to get him through the new news cycle it was just an "aspirational goal". The media will act shocked at his brazen lying for a moment and then move on.
The difference this time will be the next 4-6 weeks. If things get really bad, all of Trump's on the record gaslighting will make him a huge target. You're already seeing some Republican governors and mayors breaking with Trump. The cultist will stay with Trump to the grave, but there's going to be some noticeable fractures when states and localities get completely overrun with death and infections and they can't afford to go over the cliff with Trump.
Trump is banking on Tribalism to save him and prop him up during this crisis. But it's going to be Tribalism versus Facts on the Ground.