This is absolutely spot-on correct. Your life is so far from set in stone at age 21 that you won't believe how different 21 is from even age 25, just a few years down the road. The grass will always seem a bit greener elsewhere, but that's human nature, especially when you've just graduated college. When I graduated, I had a top notch degree (like it matters), but I didn't even have a good job that paid the bills easily. It was what I thought I really wanted to work in, what I thought I should be doing, so I took a huge pay cut to be a low-level researcher. I was so jealous of my friends who graduated and took a "boring job" that paid triple what mine did, who got benefits and bonuses, and did exactly what @anigbrowl said - they banked money for a few years and it set them up for so much success. They fostered their own interests on the side, paid off any debt or loans they had, got cars or houses, and saved up their money. Without fail, all of those friends found jobs they enjoyed far more (some of them through connections at that boring job they didn't like in the first place), jobs that let them have a greater impact on the world, and jobs that were more in line with their interests as they evolved through their 20s. And again without fail, none of them accurately predicted the direction their lives and passions would go from the time they were 21 until now.
I did the same thing, but without the added benefit of making any money like you're doing now. I had such a strong notion of what I wanted to do, and as I spent more time messing around with ideas in my spare time and learning more about what I wanted for myself, those notions changed so radically that I went from stem cell research to IDEs in a matter of years. The thing that helped me the most were the people around me. I was able to talk out all my thoughts and worries and anxieties. I was able to share in other people's interests and passions to see if maybe those were mine too. It made me feel like I wasn't alone, like things weren't hopeless, and like I had the potential to be extraordinary if I wanted to be. Ultimately the things that have truly begun to define my life came from utterly unexpected places, and almost entirely from the cast of friends and family around me.
Hang in there, the path gets clearer.