Think of how dead they would be if the insulin didn't exist. The part of the topic of insulin relevant to a discussion of trickle down economics is whether the insulin could have been researched and invented without letting people become wealthy profiting off of it. The monopoly on insulin that happened recently is one of the evil tendencies of capitalism that needs curtailed with laws, but unrelated to supply-side economics.

In the case of insulin, it was in fact invented with nothing more than research grants and the promise of fame and nobel prizes. But it also took 30 years from the first hints of what might solve diabetes until they produced a drug for it. It's an open question whether that could have happened faster with a profit-motivated company pushing the research.