Guess I'll just watch ads to finish the quest

This game has generous rewards, but it requires a huge time investment, making it actually not very worthwhile when you break it down. I've given up. There's a fast method, but I doubt it's achievable: win the league and get first place, which gives +6000 at once. However, I suspect they've included bots, and their scores increase incredibly fast, making it basically impossible to win.

Waited an hour and was shocked by the ad reward. You have to watch 10 ads to get 30 diamonds.

Too hard

If you can't complete it, just give up.

I hate all these ads

After 800, they don't give any more diamonds. You can never reach 1650.