3 main reasons for me (no particular order):

1) I've always thought it looked wicked cool.

2) I don't like paper plates, disposable razors or other consumables because I don't like having a recurring cost of time and effort to replace them. Plus, sometimes you'll run out and be screwed. I guess this is more self-reliance than environmentalism.

3) I have a weird collector's mentality. I don't need fifty or a thousand razors.
But I would absolutely love to get three identical Henckel blades (with barber notches. ) and get someone to put custom identical scales on with inlaid I, II, III. Something about me likes sets and consistency way too much. I read comics (dork!) and have two copies of one trade paperback because the first copy I got was from a different printing and the spines don't match on the shelf.