As long as BTC price isn't collapsing most won't complain too much about waiting for the few yet unsettled bets till Jan 6th (Jan 20th in some cases).
I would rather prefer to have the Bitcoins in my wallet, rather than trusting the gambling site. The exchange rates are rocketing upward and very soon we will witness a number of gambling sites closing down, vanishing with the funds of their customers (similar to what happened in 2017 December). No matter how trustworthy a particular gambling site is, I don't want to trust them at this point.