I had a look at the guide.
Would get you roughly 300-500k an hour with dedication. Very simple guide, would take a long time to get to 70mil from 300k though.
Verified*, converted 81gp to 2.2k in 3mins, if you do this in 5 hours a day you can make 400k, I suggest this for people starting to make money or with F2P low levels because takes time to get the 70m.