Yes you can be successful without a degree, but generally speaking (certainly not always) you will have to work harder/more hours to earn equal pay.
For instance, I consider myself fairly successful. I pulled in a hair under $80k last year at age 25, but I worked almost 600 hours of overtime to do it. I have friends with 4 year degrees that earn half of what I do, and I have friends with 4 year degrees who pull in the same or greater, but only work 40 hours per week.
It's highly individualistic. In my opinion, if you aren't going to school, your best option is to learn a highly skilled trade. Don't waste too much time working mindless labor jobs such as loading boxes on UPS and Fedex trucks. Even if the pay is a little less initially, its better long term to develop a marketable skill.
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