Actually this is a hard situation for gamblers whom do really make use of bitcoin because they would really be needing to deal with the fees.
But there are options to choose but that gambler must have other altcoins to save the fees.
And the other condition is that the casino must be accepting different alts. The fees really are quite of a pain theae days but there is a way and alternative.
This should not be a big issue now because almost all of the casino offers more altcoins to gamble with along with bitcoin. If anyone cant afford the high fee of bitcoin or ethereum, they can use dogecoin or litecoin to deposit and gamble. Also after bitcoin have reached all time high, people prefer to gamble with cheap altcoins more often than with bitcoin.
With btc price rise and due to fees mostly either users getting converted to other altcoins which the casinos support and deposit and take payout in that coins. Also, betting on those altcoins might be better as LTC price might not have that sudden jump which doge coin could potentially have. So need to pick the coins as well wisely while playing.