People have been risking their lives and health even for a less money or items. I think everyone risked during childhood by getting ball back that fell into neighbors yard where angry dog lives. I think in current situation, that $0.3 bet was made most as a joke, but drowned guy wanted to prove something to others. Those $0.3 were a stimulation for him to make a tiny step forward and accept challenge.

Or, we dont fully understand financial situation in their region. For us this amount might sound like a joke (I can even imagine what I can but for such amount), for them, that might be a significant amount.