
This is mostly worse than our good old friend Emergency Cache. If you play it honestly and pay normally it's only better if you hit a 20 or 21, slightly worse on an 18 or lower, and much worse if you bust. I feel that it's pretty clearly only worthwhile if you have some kind of trait synergy going with fortune or gambit, or you're already doing token manipulation.
As Elkeinkrad points out, you can pay for this with Prophetic if you have it in play, which notably improves the value proposition if you weren't using that card otherwise that turn. With mystic access, one could also try fishing for desired numbers with the new Olive McBride, although generally anyone who can run Olive can run Voice of Ra to probably-better results.
Preston Fairmont's Family Inheritance has an interesting interaction here that may make genuinely gambling worthwhile, because his resources are use-it-or-lose-it each turn unless he spend an action to bank them. With two action remaining, Preston could play 21 or Bust with his inheritance money, and then spend an action to bank his winnings if he wins big and move on with a shrug if he busts.
Finally, this card's fortune and gambit traits have some interesting potential with the premier green tutor, Friends in Low Places. Selecting gambit lets one search up a number of decent resource economy options (Bank Job, "Watch this!", Kicking the Hornet's Nest), some bonus actions (Honed Instinct, Swift Reflexes), and a handful of other utility options (Copycat, Stir the Pot, Money Talks and deck thinners (Daring Maneuver). There are also some powerful cross-class options like Act of Desperation, Transmogrify, and Practice Makes Perfect.
Fortune probably doesnt have enough hits in mono-green to be worth selecting although it has the very powerful All In and Hot Streak, but for green/red players it opens up a huge library of failure-prevention and failure-exploiting cards in Survivor.