Easy way to get legend coins?

if you finish the gaga questline, you can repeat it infinitely every 5 minutes and you get 1 coin + exp every time you complete it o_o

Finishing the line of quests got me to like 60 coins, then i just kept doing the quest during 2x.

Yeah, the quest chain is
3 for the first 3 times
+ 3 for completing it
5 of the second
+ 5 for completing it
7 of the third
+ 7 for completing it
10 of the fourth
+ 10 for completing it
+15 for completing all of them
= 65 coins by the time you're done.

Plus you can repeat it however fast you collect 30.