No since there is now way anyone can run away with the money at the end unfairly. This is all thanks to it running as a smart contract so all payments are done autonomously, no humans required.
It is however gambling since you are estimating that the pot will still grow much bigger than it is now. If you think it will keep going longer, then buy as many keys as you can to earn as much dividends as possible. Remember that dividends can be redeemed anytime once given to you.
Have you audited the code yourself and ensured that there was no backdoor? It doesn't look like there's been a single audit performed on this contract, and although the code is public it is an absolute mess and hard to read, which I quickly stopped doing since I have nothing at stake with this contract and didn't want to spend hours debugging a pile of mess.
Please be very careful with stuff like this it's incredibly risky even if there is no backdoor.
Yeah and you never want to be that guy who tells everyone to join a sinking ship xD
Code has been checked by dozens of independent Solidity teams and the contract had a testnet run. No other smart contract with gambling-like mechanics has been this safe. Yet, it is not 100% safe as you say since it could intentionally have a vulnerability (would make most, if not, all smart contracts in danger too) and of course, the gambling aspect of this. Good to bring this up though.