Id love if you kept working on this game after the jam is over!
I ended up playing this game a lot more than i initially thought i would so i found a few things that might be overpowered
as i mentioned in a different comment where i got >200 trillion score, its pretty easy to rig your entire deck to be made of 6 fives and that way guarantee a jackpot every round. by the way, im not sure if its a bug or intentional to stop players from rigging the outcomes, but one card in the deck never seems to able to be played (and isnt in the discard pile either), so for example having 5 fives in your deck would always get you -20 then your deck will run out
because of how easy it is to guarantee a perfect round every time, going all in every round (and in the first few just hoping you win) is absolutely the most op strategy and gets you effectively infinite money by round 6-ish if you do it right
making all cards 5s is really easy mostly because of one reason:
rerolling and thinning the deck never gets more expensive. if you have enough money you can easily spam it in one turn to get your deck exactly how you want it, and buy whatever numbers you want. by thinning one card and buying a five round 1, then buying 3 more across the next 2 rounds at the end of round 3 youre already ready to have a deck of only 5s, and if you went all in every round before hand your money should be alright too
as for feedback:
i think first of all subsequent rerolls and thins should cost more (you could take a peak at common clicker/idle game upgrade formulas to get some inspiration), although this should reset every round
if you want to stop the 5s strategy you can simply make the base target number prime (like 23 for example), or just have it change some rounds. if you dont want the strategy to be impossible, i still think you should make it more difficult somehow because it is far too easy to pull off
as for the betting mechanic... Yeah i think its way too op. I like how you can bet your money on the outcome and risk having no money next round but the payout is way too high and super consistent if you build a deck of low numbers (or ofc 5s)
Sorry for the really long message, I really would love to play a slightly more balanced version of the game with a few additions, it really did keep me coming back to optimize my score. If you want any specific ideas for stuff id be happy to try to think up something fun, just comment to my comment or something ill probably see it :)
thanks again for making this game