Not every 21-yo is able to come up with a business plan that would potentially make him financially free within two years. You're already saying this yourself: Do it, or regret it for the rest of your life. It's fine to fail, rarely anyone succeeds in their first try. Look at that girl you liked, but you couldn't get. You failed, but you ended up with someone better.
Easy and logical choice to be made at the age of 21, provided that the business plan is a good plan. Mass smuggling drugs into prisons with drones is not a good plan.