I imagine it's not because it's the most interesting but because market demands force them into it. Far less resources are put towards solving the climate crisis...
There are lots of people. Your complaint seems to amount to "no one should work on their own projects until the world is solved", which is not viable -- though it has been tried in the past, with great negative effects.
(Also, an aside: I think this criticism of G & FB is overwrought (and I'm 100% G&FB-free, personally). We see this snark get thrown around a lot, but almost no one in either corp works on the insidiousness++ version of ad targeting. The best&brightest at each definitely do not. They all profit from it of course, but the same can be said for all employees of large corps, to varying degrees.)
I think our discussion won’t be productive as you don’t want to consider what conditions the market plays in forcing people’s choices.
If you are instead arguing that leaders should lead, and governments should invest in the future of their people, then that message is not coming through.
The biologists working on reviving extinct species are not the workers building solar plants.
No one is forced into the jobs you're describing.
Market demands make those jobs more appealing to some. Appealing is interesting.