However, that would drop from time to time so probably a $3 fee is still fine and will be confirm in less than 24 hours.
Sometimes you could get away with a $1 fee, I remember few days ago the recommended fee from electrum was hovering somewhere at 15-20 sats/vB.
Exactly, but as what I said, you need to do it with the right timing and patience is necessary.
However, you also have a good point, not everyone can wait, some people just want to gamble right away and they will use altcoins instead rather than waiting until the fee of bitcoin will dump.
Those who are dedicated to using Bitcoin in their gambling will wait for the right time to deposit, but for those who had an schedule time to gamble will not do that, they will opt to use other currency, with Bitcoin's fee going up and down, many gambling sites have install other popular altcoin's as choice, the gambling casinos who can only offer Bitcoin and Ethereum will have a hard time attracting many players to play in their site.