Very amusing and rather deep game once you get into it past the initial bumpy entrance (pun intended): really fun and addictive stuff, thankfully with none of the risk of actually doing it for real, thank god!
I was a little bit annoyed initially where I'd buy but then get stuck with no way to sell positive for a huge amount of time. I was also annoyed about the penalty for hitting buy/sell when midair as it felt unintuitive, and I wished I could break/speed-up the cart to take advantage of highs/lows I'd sail over. However, once I accepted those annoyances as intentional design, I learned to embrace my inner day-trader and do more rapid-fire buys and sells on short sets or even single hills and the whole game opened up: really cool and fun to experience the evolution of strategy and the risk-reward in trying to hit that sell at the peak but not when you're mid-air!
I think the game has been pretty cleverly designed with a lot of risk-reward and time-pressure to both lead the player towards that rapid-fire day-trader strategy after seeing how the classic sit and wait strategy doesn't work, and to show the player just how crazy and stupid all this crypto/stock/day-trading shenanigans can be and how easily you can fail (I wouldn't blame you if the game was subtly designed to push that message by always trying to screw you over, making it trend downwards right when you buy and trend upwards right when you sell, because it sure felt like it haha). Smart and funny stuff!