This is a very poor random number generator because it is not provably fair!
To be specific, what is stopping you from setting a seed that will manipulate the final winner?
All will be OK
All will not be OK. First of all you just deleted my post that is just raising a security concern about your lottery (which raises eyebrows at my end about your true intentions).
Second, you have one of the worst negative trust ratings on this forum. If you are not using a probably fair algorithm, how do you expect any players to trust you and participate in there?