Chances to win the lottery are really low, so I wouldn't suggest depositing bitcoin to buy lottery tickets. You could deposit BTC and leave them untouched to enjoy the interest.
Since the beginning that I joined the site (9 months ago) I buy each round 50 lottery tickets without any luck for the moment.
I agree with you, you can see the winner users who are mostly new ids which are created are winning and that too with low tickets purchased. So i think this lottery system is totally manipulated by the developers or faucet owners. I am using this faucet from oct 2014 and till now maximum faucet win was 9997 and when they started lottery system not a single lottery i have won not even 10th number winner also. So i dont have faith but now i am playing for fun only to kill my free time
Lottery is provably fair, you can check by yourself that winners aren't chosen by devs.
Now we are thousands of users, so don't expect to be among the 10 lucky winners so often. We had 140 draws so far, so 1400 people max won something at lottery (supposed there's no big buyer who won several times). 1400 out of 11M users... That's why I don't spend any satoshi to buy lottery tickets, but trying my luck only with tickets from faucet and dice game.