You lead by example and give them the best version of Coach You you can give once they ask for it. The vast minority of everyone you'll ever meet who could benefit most from lifting weights will not pick you up on your offer of showing them the ropes. There's nothing you could've done differently. But there is something you can do in the future: don't close yourself off to the posibility of helping anyone at any time. If your friend comes around in two months, two years, or 25 years, you can do worse than show him how to drahve his hips up out of the bottom. For now, take solace in the fact that it's not you, it's them, and the nature of the beast. Barbell training (for injuries, and everything else) is an impossible sale. People just have to be "dumb" enough to buy it.