they aren't doing it for the planks... They are chinese farmers. They auto up there yew woodcutters to level 60 all by cutting oaks. they then cut the oak planks and sell for 500 ea. I dont know how many for 60 but look at it this way every 10k oak planks is 5m... 100k is 50m... and if they buy the oak logs for 200 ea? 200+150= 350 , 500-350= 150, 150 profit per plank and they can easily do 100k planks a day since they are botting and often use multiple accounts/ computers. In the end they sell it on a rs gold site or something like ebay.