Listen, because I think this might be a good idea. I play a game called War Robots. It's really fun, and I recommend everyone reading this to try it out. But that's not why I'm here. There is a thing called gold in this game, and is basically the equivalent of tokens in SM. But you don't have to buy gold. You can complete achievements, or better yet, earn them in battles , but in extremely low quantities (I haven't earned 6 yet). I think that if the devs considered adding this into the game, it should be like this:

After a win streak of 1+, you will start to earn tokens in battles. The tokens you earn will be increased by +1 for each battle you win in a streak.

If the streak is broken, you will lose your progress and going back to earning +1 token per battle

You can earn tokens in single player battles, as a 10% chance of getting +10 in a rewards box.

You cannot get more than +10 tokens in the battles you win during a streak.

I think this is a good idea. Like I said, the tokens earned will remain in extremely low quantities, so top players can't farm this. This is so the non-paying people have an easier doorway to better items for their mechs. Seriously, take some time to consider it.