I have seen some Gambling sites offering a deposit bonus of $1, then setting the minimum withdrawal to $20, and requiring a $5 network fee for BTC (but they actually pay only a very small fee, around 2–3 sats per vbyte, which would be 0.00000222 BTC or about $0.24).
That's why I don't go for BTC withdrawals if the fees are quite high and sometimes if the network is clogged, it adds up for more. So, if it's obvious that we won't pay for that much as withdrawal fee, just gamble with altcoins. And for the minimum withdrawals, it's not always $20 for most. It could go as low as $10 to $20 depending on the casino. And it's lower with altcoins.
Can this be considered a promotional activity or tricking the user? $1 isn’t a big amount, but most of these Gambling sites are just trying to trick users to grow their audience.
Not tricking the users, most of the promos are known to have conditions and they don't come easy.