How come riot doesn't also put champions on sale for half IP also?

Cuz they won't make money cuz people don't pay for ip ??

Because ip does not cost money and RP does that simple and same reason why skins only cost RP

As annoying as it might seem, Riot does need to make money for game maintanence and improvement. By keeping the IP prices consistant while offering RP discounts, they can make spending money more attractive to players who may not have as much money to spend.

Yes, it's a business decision, but it's also smart to open up options for lower end spenders to have that access.

The point of a sale, and this goes for ANY sale, is to increase revenue by drawing people into the store to sell larger quantities of an item at a reduced price(reducing profit per item, but through the quantity sold actually increasing revenue)

If they, at the same time, make the item easier to acquire for free... the sale becomes pointless.

So they can make money....