Stars are experience points (XP). As you collect more Stars, you’ll level up. Higher levels unlock higher Duel tiers and more benefits in the near future.
The larger the Duel tier you select, the more Stars you earn. While you may risk Bolts for losing, you’ll win the same amount of Stars either way.
There’s a lot of additional features and benefits to be released in the near future, and higher level players will be able to access and earn more. Start playing now and level up so you’ll have full access when the time is right.