College Acceptance

Almost any college or university to which you apply will require a copy of your high school diploma. While many schools offer a chance to explain "extenuating circumstances" for any missing application items, most colleges will not consider an applicant who has not graduated from high school.

Employment

A high school diploma will work to your advantage when you look for a job. According to the Bureau of Labor Statistics, having a high school diploma makes you 37.5 percent less likely to be unemployed than those with less education.

Earnings

If you get your high school diploma, odds are you will earn a higher salary than those who don't. According to The Mint, high school graduates earn about $8,000 more than high school dropouts.

Character Building

Many high school graduates go on to lead successful lives, possibly from the life skills they picked up in high school. According to the Bureau of Labor Statistics, employers often see a high school diploma as proof that a potential employee has the determination, organizational skills and aptitude for the job.

Preference Over the GED

If you're considering just getting your GED later on, consider that some schools and employers view the GED as inferior to a high school diploma.

Source:

Bureau of Labor Statistics: More education: Lower Unemployment, Higher Pay

Education-Portal.com: Why Should You Earn Your High School Diploma?

RWM Vocational Schools Database: The Benefits of Getting a High School Diploma