He is already charging for his product. The 25000 dollars would be profits from doing nothing.
Unless we are going to get into "Double Charging"
When we add rewards there is an aspect that the "extra funding" is profits and that is fine.
Let's put it like this, and this is very very simple:
Guy asks for $5000 to make his AwesomeGame.
He prices a copy at $50 to the customer, meaning that he needs 100 people to back his project to make his goal.
He works out his costs as such:
100 copies at $20/copy = $2000 (expensive for such a small print run)
Shipping on 100 copies ($10 per) = $1000
Time and effort spent: $5/hour for 100 hours = $500 per person times 3 people = $1500
Kickstarter/Amazon cut: $500
Total: $5000
He gets inundated with orders, he now has 1000 orders to fill, and the project has raised $50,000.
He recalculates how much it'll cost to have copies printed, and it turns out he can get them for half-price per unit because the print run got larger. $10,000 instead of the originally estimated $20,000 ($2,000 * 10 times as many copies).
His time spent on the project hasn't gone up at all, and he and his friends decide that the game doesn't really have any opportunities for an expansion, so there isn't really anything they can offer people in terms of stretch goals.
They do decide to pay themselves a bit more than minimum wage, though, and up their hourly to $15. $4,500 total for that line item.
They can't reduce the reward tier price, though. Kickstarter doesn't allow you to change a reward after someone's chosen it.
What do they do with the extra $10,500? Do they give every backer $10 back? Do they keep it?
What happens if this wasn't the end of their campaign and suddenly they don't have a thousand copies, they have FIVE thousand and their price-per-unit costs go down even more?