Russia has nothing like the F35 and Ukraine has planes too (although not as great). Once Ukraine got F16s they had an impact (even though it's a very old model).

The idea of a drone swarm is science fiction at this time. First, it's not 10,000 drones. Maybe the low quality stuff Iran builds is that cheap. A good western drone will be expensive but also of far higher quality.

If you try to send a drone cloud then they are easily detected and you can just shoot them down. If you send them one by one then they get detected one at a time. A few get through as we see with Israel who dealt with well over 30,000 drones/rockets over the past year... But it took them a year to launch 30,000 rockets/drones. They did very little damage.

You need logistics to send them out big logistics are a big target for an F35. If you do it from far away (like sending drones from Iran) then radars have a lot of time to pick them up and shoot them down. If you do it from close by (like Lebanon) then some might get through but the F35 in the sky will destroy you very fast.

Finally, they all need to fly autonomously which is flawed. You can take them down like ducks in a row. Any soldier with a smart scope can just bring down a drone. Not to mention their deep vulnerability to electronic jamming.

I used to think like you as an engineer. But having spoken to people who actually know this stuff I understood the difference. Yes, there is a price disparity which is why the Israeli army has both drones and F35. Different tools for different jobs. A drone can't carry the damage and logistics an F35 can. But sending an F35 to shoot down drones is a remarkable waste of resources. That's why Israel is working on energy/laser based defense systems which will make a swarm of 10,000 drones completely useless but won't even scratch an F35.