Bitcoin gambling is not illegal because in order for an online casino to operate they need to register it, they are paying tax and they have their address listed in their website. If a casino is not legally registered how can we trust them , how can we play on their website thinking that they might run because they don't have any obligations.
Even if a casino is registered in a country with lax gambling laws they could still end up scamming you.
There are enough stories of people winning big jackpots in traditional casino's and not receiving their money.
Okay, some Bitcoin casino's may not be registered, but they do have a proven track record, which makes it pretty safe to play there.
Ofc I wouldn't leave any funds on your account if you're not playing.
Also, most good Bitcoin casinos have instant payouts.