Yea people are earning the eddies with the epic and legendary grenade crafting recipes. Craft then break down then sell the excess to vendors and sell machines. I've spent a lot of time just clearing out everyone of their cash using auto macroing crafting, I couldnt see anyone being able to afford most of the stuff the game offers. Would take a crazy amount of time to earn enough ed's to get all the vehicles. Granted, in total its probably about a 1 million but, not entirely impossible.
Even more so, I am full built into crafting (20 int 18 tech) and to max out weapons through upgrading is WAAAAAY more expensive than buying vehicles. Some weapons like the Overwatch, I am dumping in 24 of each legendary mat currently and its still upgrading. I have the base dps up over 1,200 (4000 base damage) with headshot crit's over 240k. Many of my other smart weapons are at that level as well in terms of upgrade but, yea do the math there. $1000 eddies for 1 legendary mat. That's about $50,000 per upgrade at this point.