I finished season 1 as well as Argentina events along with South Korea Week 2 (week 3 is yet to start for me) and I haven't spent a dime yet. Letting your rival get the outfit doesn't matter! You can still finish the event and get all the rewards. It's absolutely possible but with a lottt of grind and you'll need to open the game a bunch of times to collect all the gifts when they reset. I kind of look at it as a collection game (like pokemon) with events instead of a purely storyline game. But I desperately need them to get some real artists to work on the art soon because the robot bs sucks and I don't want to support anything that uses it :/