Why will you buy BFG tokens if your intention is just for fun alone? You will pay transaction fee when converting your BNB to BFG instead of directly playing using your BNB to avoid extra fees. BFG tokens is a utility token of the casino so you can invest on Betfury success by buying since they are burning token supply using part of Betfury profit so it means that price will grow overtime due to decreasing supply.
Other utility of BFG tokens is really for betting purposes but it’s not limited on that feature because use it on staking and farming too.
The swap fee in BSC is not so big to worry about it. In addition, it should be noted that if you buy BFG tokens, then these tokens will not be limited in any way after the deposit on the Betfury site. At the same time, if you wager BNB or any other coin, your mined BFG tokens will be locked for six months. This means you won't be able to withdraw some of your BFG and sell it if you suddenly want to do so.