Nothing but yourself and how good you are at getting someone to vouch for you. If this is your only higher-education option there has never been a better time for accessibility to information. If you can comment here you've got pretty much all existent knowledge available with few exceptions. As a non-STEM bachelor's degree holder the largest value my diploma has is proving I can deal with bureaucracy and bullshit for no less than four years, and I'm not completely brain-dead. It helps to have an institution older than anyone alive backing those claims if I'm dealing with someone that doesn't know me.
I knew a guy that dropped out of high school the day he turned 16, got his GED, and basically self-taught himself how to basically be a sysadmin. He basically ran IT for a few small business clients before he was 18, definitely knew the most on the team. When I worked with him he was getting $10k for a month long contract and it was a lower-paying contract for him. I know a different guy that dropped out of college for a programming project he thought might be a good idea. He's built it out into a company with a $1B+ conservative valuation. Even if they BK tomorrow he can go back to any college with that work experience and wrap up undergrad.
Those are the two big successes I personally know of. I know of at least 20 people from HS through undergrad that ended up dropping out for some reason or another. A few of them had solid ideas too and felt they did not need to finish formal schooling. To say their ventures failed would be an understatement. I guess my bottom line here is that you need to be honest with yourself if you contemplate that path.