Earned through various activities. Spent at vendors throughout the world. Karma is a non- tradable account-based currency that players can use to purchase items from karma merchants, including Renown Heart NPCs and master craftsmen. The amount of karma you hold can be seen in the Wallet .
All the other ascended gear is easy to get. You're also not taking into account some of the highly valuable items that came in the Chests of Black Lion Goods. Some people do, yes, but is the average player really going to spend gems or real money on Black Lion Salvage Kits, Mystic Forge Stones, or Black Lion Chest Keys?
There are reward tracks that give exotic gear with Viper stats as a stat option. The tracks are: Bloodstone Fen (Headpiece) Ember Bay (Headpiece and Shoulders) Bitterfrost Frontier (Gloves) Lake Doric (Headpiece) By doing a combination of these you can get at least the headpiece, shoulders and gloves.For Armor-You can get ascended armor by raiding (a meta started exotic set is all you need to start, trade the raid currency directly for gear boxes) playing PvP (cashing in your shards/marks earned thru reward tracks), WvW (doing exotic armor reward tracks and upgrading the armor to ascended status), and of course through Crafting.
You can get Ascended gear from most endgame things. A lot of routes require crafting for on demand gear. PvP, Fractals, and WvW all require multiple tokens for gear, on top of other rewards obtained in those game modes (and a little bit of gold). These tokens can often be rewarded to you, but the easiest way to get them is to craft them.