What is the math behind a gift marketing company with game mechanics?

Question

Marketing

Hello.
I do not quite understand how to calculate the numbers in the framework of such an event. Users on the promo site accumulate points for targeted actions - at the end of the promotion they exchange them for gifts. It is not clear how many points "gifts" should cost and what is the amount of reward for each action taken by the user. The priorities for action are more or less known. How to avoid a situation where gifts may simply not be enough for wealthy users?
You can, of course, not hang up the "prices" for gifts - and distribute them among those who will be in the top at the end of the promotion. But the first option is more interesting.
Thank you all in advance for your participation!

Answer 1

As a result, we settled on a pyramidal scheme: the one with the most points receives a super prize. The next 10 winners receive the 2nd prize, and so on.
It's easier

Answer 2

Do you have product sales statistics? You can see how much is sold, sum up. This amount plus 10-20% divided by the total cost of gifts. You will get how much you need to invest real rubles to get one "gift" ruble.
Example: There are 10 products in the store with a total cost of 1000 rubles. We bought gifts for the action worth 60 rubles. Suppose that, according to statistics, we sell goods for 200 rubles per month. Let's take with a margin of 20% more (suddenly, they really get rich) and suppose that we expect sales of 240 rubles. Then, dividing 240 by 60, we get that for every 4 rubles spent, 1 "gift" ruble is due. Now all prices can be divided by 4 and get how many bonus points the buyer will earn by purchasing this product. Round down, of course.