You'd have to be around average for a developed country.

Assuming there are 25 kids in the bus, it would take about 14 months' worth of the US nominal GDP per capita for the AMF to save as many lives (not to mention that the kids saved by the AMF will likely have less QALYs ahead of them than the kids in the school bus). If you only count discretionary income, it'd probably take decades for “one person” “around average for a developed country” to do “much better than saving a bus full of kids”. (And note that the average is a lot larger than the median.)