It is better for a 16yr old to sail the world alone vs sex with a partner over 18yr?

So, how is allowing a 16yr old to sail around the world alone less risky or less detrimental than allowing them to have sex with a partner over 18? I know the argument a 16yr old is not mature enough to consent or enter a liaison, affair or fling with a person over 18 but then how are they smarter sailing the world alone where the outcome can be captured and sold into sexual slavery, murdered for their water craft, frozen to death, or end us bobbing in the water as shark bait etc? It is almost like people applaud the activity that can end in death over one where their might just be a broken heart but the teen lives. Or is this just an American thing?