We like to celebrate our successes. We have graduation parties, celebrate the completion of projects, a big sale, etc. It's easy.
How do you deal with your failures? Do you try to forget about them, sweeping them under the rug? Maybe you're embarrassed about the failure or have been punished for the failure.
I think it's important (perhaps after some time has passed) to review your failures to see what might have gone wrong. Is there something specific you can avoid in the future? Is there a pattern emerging where similar situations end up the same? Recognizing patterns is what we as humans are good at, but we need to be looking for them. Burying your head in the sand and hoping to forget about a bad experience increase the chances that you'll end up in a similar situation again.
Also, leaders shouldn't punish people for failures (other than perhaps ethical failures - and certainly criminal failures). It will make them afraid to take risks, try something new, or be creative. How can you expect creative solutions to difficult problems if the consequences of failure are too great.
Mistakes can be golden if you learn from them.