I am a firm believer that two things that can change the world that we (the US) are holding back are Psychedelic treatments (by the DEA) and mesenchymal stem cells (FDA and big pharma).

Tim Ferriss has done a ton of work on Psychedelic treatments and if you are looking to go down a rabbit hole this may be a good place to start - https://tim.blog/2021/03/31/psychedelics-101/

Mesenchymal stem cells are cells pulled from umbilical cords - more info here https://www.cellmedicine.com/ but they are literally the fountain of youth and can solve so many issues we have. You can't patent a biological so big pharma has been blocking it for years through lobbying of Congress and the FDA.