I don't come on here for a very long time...and then I do and see this question. I'll answer and explain how I view them - please be kind...
There are a few reasons I enter competitions. The first might seem silly to some, but it is by far the main reason for me: I dive and shoot with my husband a lot (a longtime pro UW shooter), and he is very skilled - so skilled that sometimes, it can be just painful to see what comes out of his camera (I commonly walk away from his downloads muttering, "I suck!" to myself). However, we work together a lot - both shooting and writing. I could do this and simply work off of his reputation, but I didn't like the way that felt. I wanted to develop my own reputation separately from him; competitions are one way to do that. The second reason is that when I am very fortunate, it can help subsidize my obsession, which is quite pricey . The third is that when it works in my favor, it is a complete and total thrill.
The problem? Competitions can be expensive...and there are just so freakin' many of them! Also, they are pretty much a crapshoot. You can enter a photo somewhere and get a huge placement and turn around and enter it somewhere else to not even have it get to the final round of judging. But this is art, and art is subjective, and you never know what the judges will or won't like. I do feel that luck is a big part of every win, whether it takes place in the water or in the judging room or both. Not placing really isn't losing, although I know the feeling and have had to remind myself of this.
Competitions are a lot like gambling. As such, I have a budget for competition entries, and I stick to it very strictly. (Some competitions are off-limits because I don't like the rules or reproduction policies. Some are more attractive because I admire the judging panel. But after x dollars have been spent, that is IT for the year.) I assume that I will be donating that money. Sometimes it works out, many times it doesn't, but no matter what, I have learned a lot and feel that I have done at least a little bit to achieve some of major objective #1, at least that's my hope. All that said, I am well aware (as are all savvy photographers) that those entering competitions represent a very, very small subsection of the skilled, fabulous shooters on this earth - most of whom, like you, can't be arsed with it. That is plain fact.
Like Tim, I am a huge fan of shootouts - same water, same conditions, same sites, same day, limited processing - that is as pure as it can get in this day and age. I wish there were more of them!