Ever been on a trampoline? I have. It's perfectly possible for me to gain an altitude of 20 feet or so. I don't do it. Why? I'm fully aware that I could do myself some real damage if I get it wrong. Now all the Apollo astronauts, save Jack, were test pilots. Their distinguishing feature among test pilots was that they were still alive to tell the tale. You don't get to stay alive as a test pilot without being aware of when to jump as high as you can and when to tread carefully. It's probably not a coincidence that the most accident prone and 'jumpy' Moonwalker was Jack on Apollo 17. He'd probably not been in enough 'close calls' to fully realise the precariously dangerous position he was in.