Stowers has not been a member of the Forbes 400 since 2000, but unlike most members who drop off, it wasn't because he lost money or died. The mutual fund tycoon--he started what became the American Century fund family in 1958--decided to give $1.2 billion to endow the Stowers Institute for Medical Research in Kansas City. Since then he and his wife Virginia have given another $700 million to the institute, which performs genetic research targeted at advancing the understanding of cancer, diabetes, heart disease and other conditions.