As far as i know, every business out there is trying to get money out of you. The good news is that they give you new and improved toys in exchange for your money. The bad news is that they use a good chunk of that money to research and manufacture even better toys to get even more money out of you
You don't have to get the new toys (i like my cameras cheap and outdated because they lose value way too fast) and you have to keep in mind that overall, photo gear is no more of an investment then your car is (they're not, unless you at least cover their cost by using them - for professional photographers they can be gorgeous assets/investments, easily covering their price).
So as long as you keep your liabilities low cost (buying SH) or you're a pro, you shouldn't expect to lose any less money then you did when you bought your brand new LED TV or smart phone. For example,since I'm not a pro, i paid for my SH 5D+35L+85L2 just 3700euro. And I should recuperate a reasonable part of that money, even if i were to sell them 5 years from now. However, were I to buy them new at the time they were released, i would have paid around 6500euro, losing a huge chunk of that money even today.