It is just a wallet to send the remaining balance to.
I had a few occasions in which I had like some 3k satoshis. So I just thought if many of the users will simply send a few satoshis left in the wallet, (suppose you deposited 0.01 BTC and made a profit and withdrew / lost most of it that you are not interested in betting anymore, etc. and you still have a small irrelevant balance left, you could send it here.) it would gradullay grow big enough.
You are supposed to send it only if your balance is too small. No need to send it as a donation or anything. If you would like to donate, send it straight to Dabs address, etc.
Thank you.