Seriously.  If you walked up to a rational person and said "Here, I know you want to skydive so here's a parachute.  But there's  a 70% chance it will malfunction and may even fail completely" do you think they would take it?    But no " I know you want surgery, but because of your weight, theres a 70% chance of complications and you may even die" is completely normal to these people. And they cry about it.