Dropoutprevention.org is a good resource in finding out how school can affect a person's life. It lists five reasons and uses real world statistics to show that people are more likely to be successful in life if they stay in school. Gocollegeny.org also provides several reasons to graduate.
On average, high school dropouts are more likely to be unemployed and are also more likely to have to apply for and receive public assistance. They also tend to earn less money than their high school graduate counterparts.
Additionally, about 75 percent of America's state prison inmates, almost 59 percent of Federal inmates, and 69 percent of local jail inmates have not received their high school diplomas.