Good game, would enjoy if you could see upcoming upgrades to know if it's worth saving for a better one. Prestige multiplier not being tied to progress kind of makes it optimal to just let the timer run out over and over until multiplier goes up.
I plan on making some reworks for the full release regarding upgrade progression and and a possible prestige rework once the game jam and my exams are over, and I would love to hear feedback on any possible changes for the full version!
Please note that your prestige multiplier is in fact tied to your progression, as the multiplier increases by somewhere around a 20000th of your total cash earned rather than your money shown. I hope this helps!