Success. Winning. Being Right. These are things that are highly valued, sought after, and are generally pursued by most people, and rightly so. However, I think that too often we overlook the inherent value of being wrong once in a while, and that we do so to our detriment. Just as there is value in success, there is also value in failure - you just need to know where to look.
Knowledge: The very first commercial software package I conjured up entirely on my own was called "Back In a Flash" and was, I thought at the time, very well done. Only it didn't work very well - while it generally did a good job backing data up, it was less successful when it came time to restore said data. It also didn't work with large systems, and was particularly slow. It was a failure. The next package I wrote was called "Back Again/2" and incorporated many lessons I had learned from the first time around. It became the cornerstone of a company a friend and I founded in 1994 and ran successfully until I sold in 2000. Without the initial failure and the lessons it taught me, I could not have been successful later on.
Practice: One of the smallest parts on my experimental aircraft is on the tail and is known as the trim tab. The trim tab is a thing of legend among builders of this particular type of airplane; the angles required for the various bends vex even the most dedicated builder. I was no exception; I had to build it three times before I got it right. However, I gained valuable experience in forming aluminum sheet metal, drilling out rivets, and more.
Perspective: In the midst of a seemingly important task, project, or other endeavor small problems may seem huge. Any entrepreneur can attest to this - many problems can seem like catastrophes. During my time at my first company, there were many such "catastrophes" which turned out to be nothing more than a minor irritant. In the midst of the issue, however, it was next to impossible to recognize that. The stress and heartburn that was repeatedly experienced (and meted out, too) was not necessary and at the time probably did more harm than good. Without those problems, however, I would not have gained the perspective that some problems are more important than others, and other problems may in fact not be problems at all.
Humility: This is perhaps the hardest thing to take away from failure, but it can also be among the most valuable. Humility isn't about being meek or timid; rather, it is knowing ones own limitations. I had the opportunity to join an internet startup a while back as a side gig. I thought it would be exciting, and it was, but I learned the hard way that it is nigh impossible to juggle a full time job, a family, a homebuilt airplane project, and a startup commitment while remaining sane. I didn't succeed in that endeavor, and I learned where my limits are. There are folks who could do all that without breaking a sweat, and my hat is off to them - I cannot.
Although success is the ultimate goal, don't discard as useless the failures you encounter along the way. They may prove to be nearly as valuable as your successes, and perhaps more so - if you're not making mistakes, you're probably not making anything.
One of my worst failures has been failing to learn everything that I could from failed attempts at various things. How about you?