Sharing it will help you to record your win. It will be saved on the Internet after your sharing. If you don't share, and don't save any screenshot on your devices, you will never be able to find your past wins in future.
You have your bet slips in the account and have proof for your bet and sharing it with people is just an extra boost or promotion way for gamblers and casino.But yes it give you confidence boost whenever you win big amounts and have that curiosity to share it with others.
Rollbot NFTs have different use cases than BAYC NFTs so I don't think it is a good comparison here.
I am not comparing both of them but have said that many gamblers who have wagered over Lootboxes can choose which NFT they want as winning gift and then wager on it and some players were Lucky to get BAYC NFT worth million dollar also through it.