Nope. That's totally cheating. Here is why:
-Player A: starts today, plays 3 hours per day without spending money, gets a reward from the leaderboards equal to X;
-Player B: starts today, plays 8 hours per day without spending money, gets a reward from the leaderboards equal to Y (where Y>X);
-Player C: starts today, plays 1 hour every 2 days, spends a lot of money, gest a rewards from the leaderbords equal to Z (where Z>Y).
It's as if player C uses a cheat engine table to multiply the resources in game aka cheating.
In game purchases are ok only if they aren't lootboxes and/or with an impact on the game. Refiling the challenge tokens on the league with kobans is cheating, since you can purchase kobans; same goes for epic/event pachinko, where there is also the random part.
It can not be simpler than this.