I think it is more fun NOT to keep track of how much I am spending and how many times I am not strong enough to pull the sword out.
I ride for a while, then I go play ghosts to make up the credits.
It's like gambling in real life: go to the horsetrack with a spare $20 and enjoy the day until it is gone, then stop betting. You don't spend all your savings on it. When your fun money for the day is gone, you don't bet again until another day.
In VMK, you ride a bit, then make up the credits, then ride some more if you like. Don't run your credits all the way down. Don't EXPECT to win anything. You are buying the fun of the chance of winning, with a cute ride and fun music to boot.
Happy playing.