It takes around 2 hours to finish all of the Daily quests which will get 1,500 Coins. 1,500 x 7 = 10,500
Finishing all of the Daily quests every day will also finish the Weekly quests at the same time. Each Weekly is worth 2,000 Coins and there are 5 of them. 2,000 x 5 = 10,000
I befriended a lot of people over several message boards for the Alliance system. I dont remember exactly how many Coins you get from a Tier 10 friend but it's close to 2,000 and the top 5 are counted.
And there you go, how to get 30,000 Coins a week by playing 2 hours a day casually.
Also, as
yet_another_alt
said, people arent going to buy cosmetics for every Javelin, just the ones they play the most. They're also not going to buy every Vinyl, or every Emote. I havent bought anything yet, so Im over 200,000 Coins. So, when a Masterwork or better armor pack that I really want is released I will have more than enough Coins to get it.