You are competing against college graduates
If you are just starting to try and crack into this industry, you will be competing for jobs against college graduates. Unless your talents or background make you stand out, hiring managers and HR may discount your resume for a person who has a degree.
College graduates earn more
The average college graduate makes about $20,000 more each year than those with only a high school diploma.
Limited job choices and glass ceilings
A lack of a college degree can limit your choice of jobs. Many professional and business jobs require a college degree. You may protest and say that you have done well getting hired at numerous IT jobs - but what about those positions you did not get hired for or never heard back from in the first place?
If you already have a job and want upward mobility to a more senior or management role, a lack of a college degree will hurt your chances of getting the higher level position. This unseen barrier is known as a glass ceiling.
Measurement of achievement
Obtaining a high school degree does not show you have the skills that hiring managers are looking for. Many news articles have discussed how a certain percentage of high school students are graduating with only a 4th grade reading level. Therefore how can a manager gauge your skills? A college degree is a measurement of performance when a hiring manager has few metrics to gauge you on. Obtaining a college degree proves that you can read/write well and that you have developed reasoning skills to function in the work place.
Finishing a college degree shows hiring managers that you are committed to starting and finishing a project. A college degree shows that you can set goals and achieve them. It also shows that you have the mindset of a doing something good for long-term gain.
If you obtain an IT-related degree (e.g., Computer Science), it will give you a background in computer fundamentals, whether that means understanding algorithms or handling interactions with your teammates on a large project for a web development class.
If you do not have any work experience in your career, many colleges provide internship programs. Interning offers you a direct link to employers. Being an intern is an excellent way to get your feet wet in the workplace.