The only thing "dumb" is climbing to 9000' part. Which DJI drones can't do. Maximum is 500M from launch or 1640' and even then you wouldn't use 50%, depending on whether you did so directly over head or within 60' from launch. IF you did so outside that parameter then Smart RTH would kick in and land you before battery would die easily, inside 60' then your critical battery setting would apply, pretty sure you would land again, no battery issue. But the short answer is even if you could climb to 9000' and had 50% left you would easily make the decent as coming down is greatly reduced on power drain. There are a few varibles but not worth discussing, but I am sure someone will, so I will leave that to them
If you want to see the fun, you could climb to max...do a CSC (Kill switch) let it drop 1000 ft and CSC again (Restart/Arm)...a few videos on YouTube...not for the faint of heart

YouTube search: "DJI CSC restart"