Ok, assuming they’re not totally stupid, tell them to look at a plane in the ■■■■■■■ sky. Doesn’t it seem pretty ■■■■■■■ slow? I mean, you can point your finger at it and keep following the damn thing as it moves.
Now tell them to stay right next to the runaway as an airplane lands. Assuming they don’t die from the experience, ask them how much of the ■■■■■■■ airplane they could see in the instant it passed them by. And take note a plane landing, flaps on and all, is flying MUCH slower - in fact as slow as safely possible - during landing.
Imagine being right next to it as it flies by at cruise speed. This is why you can follow jets with your dirty fingers as they cross the sky. The perceived momentum is much greater as it gets nearer.