I conducted a very rudimentary research on wealth gain in BDO. I simply screenshotted the wealth toplist along with the various profession toplists and checked for names appearing in both. Please note that the toplists are dumb: instead of showing the results of the server (there is one EU server), they show the results of your active channel (there are 20+) and only for the online players. I have no idea why. Still, it gives us an impression:
The top professions are all active:
- Growth is actually level gained which very strongly correlate with monsters killed. So these are simple grinders killing monsters day and night. Unless you bot, you have to constantly be at the keyboard.
- Gathering is moving around the World to find mines, herbs, skins, trees and other collectible materials. This is also an active profession, you have to move manually and find the items, though the number of keys pressed is much lower.
- Alchemy is a crafting profession, but most craftables don't stack, so you have to craft short batches and then manually list them as singles in the marketplace. I used alchemy back then and found it way too grindy.
- Hunting is about half as popular among the top wealth players as the very active professions. While it is active, the most lucrative game is whales that needs just one player to control the boat while other just auto-shoot.
- Trade is moving specialty items (either purchased or crafted) to distant locations where NPCs take them. The activity is typically 10 mins wait and few key pressed then 10 mins wait and few key pressed ... for hours. It's best for players who are near their computers but don't want to press many keys. I did this extensively and it pays well (my trader is another character, that's why I'm not on the toplist).
- Fishing needs you to move to a fishing spot and go AFK. This allows hour long AFK periods, but as you are in the World, you can be ganked or attacked by monsters, so some supervision is needed.
- Cooking needs you just to stand by the cooking utensil for about an hour AFK and then move to the next utensil. When finished, you must move to the marketplace to sell.
- Farming needs active clicking on your farm, and then you can forget it for a day. It's the least popular activity.
- Processing is the most AFK activity and it's very popular. It needs you to start a batch standing next to the warehouse and go AFK for several hours. You can sell the products right there at the Warehouse.
- Training needs you to sit on a horse or cart and set a loop and go AFK for several hours. As horse market is small, only few people can make profit of it.