Why is magenta ink in such high supply?

[Texshooter]

Every time I buy Epson ink carts for my Pro3800 on Ebay it seems the availability of Magenta outnumbers the other colors 10 to 1. I'm curious why. Does magenta get used up by the printer more slowly, so people don't need as much of it?

 

[J.Emmett Turner]

I’m pretty sure it’s because the K3 and Vivid K3 printers share all the other K3 colors. This makes MK, PK, LK, LLK, C, LC, Y useful to use for both where M and LM are only useful for the older K3 printers. Extracting ink to refill carts makes this gulf wider.

 

[J.Emmett Turner]

More specifically, Epson Stylus Pro 3880 users are buying all your PK, MK, LK, LLK, Y, C, and LC. They have no use for your M and LM, since their machines use VM and VLM instead.