Ignore bored players trolls who don't know jack shit about the new Season 3.
You want EASY caps? Sell Rotgut. Collect Fruit and Wood, and put it all into a still. One bottle of Rotgut is worth like 125 caps. You can easily clean out a vendor's money supply by selling hard liquor.
Another way to make money fast is to kill TellTale bosses, or do Combat Jobs in the Hub, NCR, and Junktown. All the gear you find can be sold. Anything broken can be hoarded and traded in for Bulk Order Jobs. Mix and match it all for maximum profit and XP. 12 Bulk Order Jobs = 1 Free Random Blueprint. You can get Combat Armor worth 100k.
There are many new public locations and dungeon modifiers. Raid some locations in game. Search the maps, there's a lot of secrets, and all items respawn with time. If there's nothing there, come back later. Most items dropped have 100% condition to them... which makes them worth a lot more money to the right vendor. Each vendor is unique, find the best vendor for each item.
Lastly, you can buy Pre-War Books in the L.A Library. Sell those to Historians. There's one in each town. Their prices are randomized, but you can make a lot of money!
If you can't make 20k caps without much effort in an hour, you're doing it wrong.