There are a number of reasons, but I care not to argue it. That is what I believe.

EDIT: I also don't believe the future will be very different from now. I mean, what kind of really big advances have we made in the last two thousand years? Sure there have been advances in all sciences and generally speaking the quality of life has improved, but nothing of significance has really happened. We're not travelling through space. We still live on planet Earth wearing clothes made from animal skins and cotton plants. The three major differences between then and now are:

1. We can communicate much more easily; information is free.
2. We can kill eachother more easily.
3. We can heal eachother more easily.

I'm sure that in a hundred years, next to nothing but clothing style will change.