People are trying. We want to cure cancer, and find effective general-purpose antivirals, and help people maintain healthy bodies, and figure out how to repair hearts, and cure diabetes, and fix autoimmune disorders, and figure out general-purpose gene therapies, and work out what exactly is up with the gut microbiome, and make prosthetic ears/eyes/etc, and then there's the brain...
There's only so much that you can do with the technology we have right now. Advances in other fields will eventually help, but you can't just spend a trillion dollars and make people live an extra decade.
Anyways, wouldn't significantly longer-lived people exacerbate climate change? You'd have many more people on the planet, and individuals would accumulate much more total wealth to spend on wasteful consumer goods thanks to the power of compound interest.