Some websites have similar jackpot like this.

IMO, this kind of jackpot more profitable to a user who can be using a bot transaction every time someone deposits/buying the tickets then the bot will react to buying the ticket too. It makes him become the last person who buying the share, now the question how you can handle this kind of activity. I mean this is not really fair who someone who buying a share/jackpot by manually.

Cause of that is, I more like it a jackpot using a random generate random from the smart contract to determine the winners.