Basically, we're currently at a stage where costs are dropping much faster than the rate at which the value of genetic information is increasing - in other words, you and I will be able to afford a genome sequence long before science will be able to tell us much about what it really means. However, the beauty of a genome sequence is that (unlike 23andMe-style chips, which are constantly being replaced by higher-resolution models) it never becomes obsolete. Once you have your entire sequence sitting on your hard drive you can simply sit back and wait for new associations and techniques for assigning function, which will soon be appearing at an exponentially increasing rate as technology improves.
In other words, the data appreciates. But unlike buying a home mortgage, there is going to be a mass drop in the cost in the near future. This figure illustrates the point effectively. To some extent then the analogy to the housing market breaks down. In many regions of the world fixed stock of land means that values will increase over the long term (since populations and per capita purchasing power are increasing) so "getting in early" makes sense. Rather, it's like buying a Kindle; everyone is going in that direction at some point but early adopters are going to pay a premium for gaining access to that utility bundle before the rest of us. Of course, the very fact that we're mooting these choices says something about the state of the game.