Complexity vs. Difficulty
People are inclined to prefer complexity to difficulty. It's our most defining characteristic. Instead of expending vast amounts of carefully collected food calories to accomplish a task, we'll instead devise an elaborate system that accomplishes the same task with far lower cost (in terms of energy expended). For instance, a long time ago, someone figured out it was a lot less work in the long run to build a fence around a bunch of cows than it was to go wandering through the forest every time you wanted something to eat. This is how we've been able to succeed as a species.
People have become extremely good at this -- we can now do most any task that we require without expending any significant food energy -- we built machines to make our work more efficient, and then we motorized those machines so that we're no longer even contributing the base effort for these tasks. This is all brilliantly complex, and the end result is that most tasks are no longer very difficult -- procure the right machine, turn it on, and you're mostly done. Difficulty then, is associated with the expenditure of food calories. Millennia of evolution have conditioned us for this, and it's very difficult to overcome that. We've survived specifically by not wasting food.
But, substituting complexity for difficulty isn't always possible. Running a marathon is the opposite of complex, but it's extremely difficult. Losing weight is another such task, which is directly opposed to our evolutionary programming. When trying to lose weight, instead of hoarding food calories, we are trying to shed them. This is not a complex task, the solution is simply eat less food. It is, however, very difficult -- that simple solution requires overcoming instincts created over thousands of years. Because of this difficulty, human intuition is to try and find a way to substitute complexity for difficulty. There are a million different diet plans that attempt to do this. And people pay money for them, because we'd prefer a complex solution to a difficult one. Ultimately though, they all boil down to some combination of eating less and exercising more, because that's the only feasible way to complete this task. (Surgery is actually a pretty good solution in terms of preferring complexity to difficulty for this problem, but it causes other issues.)
Another area in which I've seen this same problem crop up is in personal finance. The world (or at least the US) is full of people having difficulty managing their finances. Personal finance is a more complex problem than weight loss, but it's still vastly simpler than many other tasks, for instance building an internal combustion engine, or trying to model the stock market. This problem has a simple solution: Don't spend money that you don't have, and save some of what you've got for a rainy day. That one sentence, if followed, would solve 90% of people's personal finance problems. Again though, we're at odds with our evolutionary programming. Our instinct is to hoard as much "useful" stuff as possible, where "useful" probably means "impressive" or "nourishing" -- the sort of things we think will attract friends or mates, or be tasty. And as such, there's an industry built up around selling complex solutions to this difficult problem.
The challenge then, is to recognize when adding complexity doesn't actually reduce difficulty, and reject these solutions to problems.