Correct that it's not entirely luck, at the moment its price is being propped up by Bitfinex. Whenever BTC value starts to dip below 10K USD, they just print more Tethers (USDT) and start buying up coins at above market price...and there's a new upswing.
blackjack tables are based on supply and demand. the margins on blackjack are ~51% in favor of house. if they don't get enough traffic, a swing could take the house. So if there isn't enough demand, than it's not financially feasible for the house to play those odds.