Rules are like in lottery, but here everyone knows who is 'winner' from the beginning.
Collected coins (gift) are going straight to person who is 'less rich than donators'.
How are you planning to choose this person and how will you know he's "less rich"?
What stops this person from just running with the money instead of donating?
I don't think that Bill Gates is playing on lottery
But according to second problem, you've right. We can't be so confident. I'm thinking now about neutral account, where will be sent BTC's first. But what then. Good point to resolve now.
EDIT:
Or maybe simply 25% of collected BTC's will go on next stage and there will be no duty to be donator?