So at max rank Roko Sensei gives 29.5k money, if you chose x10 battle he only gives 266k, pretty sure it's a bug, can't really post a screenshot since I dont have any BPs currently.
Nvm, probably I got an item instead of money,
My suggestion is simple : give us a choice to buy multiple skillpoints instead of 1, like in those stupid clicker games. I'm not really into clicking the same button a million times. x10 or x100 multiplier should be fine I think.