I looked at the rates for the Pipes (the gacha loot boxes). Focus racers and their karts and gliders are at 1% each out of 100 pulls.
That means in order to get a full focus set, you would have to use 500 Emeralds (premium paid currency) at max.
People suck in this game but yeah getting first isn't the end all be all you also have to score high which is conveniently based off of which racer you're using lol. Or how many items you hit which is based off of which racer you're using. And if you need good items you need a good glider which is based off of your gacha luck. So it all ends up being gacha luck.
I believe the rates for the pipe are locked though. Once you get bowser you won't get another copy of bowser and the odds of everything else increases accordingly. Once you've done 100 pulls on the pipe you've gotten everything out of the pipe including the special thing. So it's not TOO bad, but yeah ouchies. Maybe once you have bowser the next time a pipe has bowser you don't have to worry about getting him and the odds increase for everything else. You know?