Peanut butter becomes dry

Well, you could shell out for a commercial nut butter mill, if you had an extra thousand bucks lying around. But otherwise the answer is probably not. I believe that commercial peanut butter makers grind the nuts between metal plates, which gives the very fine texture. At home, you're presumably using a food processor, which can't make thick-textured pastes very fine.

Some health food stores have nut butter mills, though, so if you're looking for freshness, you can grind just before you buy.

While the grinding of peanuts produces a paste we call peanut butter, a food processor may be slightly better equipped to handle them then a coffee grinder, especially if you want to blend coffee with it again. Peppercorns are harder and they can be done in a coffee grinder, but peanuts would likely result in a mess that would not easily be cleaned, and somewhat chunky peanut butter.

edit:

As stated in the comments below you may get some good headway with a blender. I had a crappy blender at home, but peanuts may be easier to grind than thick smoothies. But again, cleaning may take some time afterwords. But blender would probably be more effective than a coffee grinder.

Peanut powder can be made by freezing the peanuts I believe, very cold. A part of the modern cuisine. I think you would need liquid nitrogen for it. Source from Tech stuff podcast, title of the podcast was Molecularly Gastronomical.