You need gazillions of green packs, which means you have to buy them with tokens, which means you have to invest tonnes of money.

Or you may be lucky to live in a country where they give you hundreds of promotions. Some people from some countries claimed to harvest hundreds of tokens and packs per week. It took me almost an year to amass 300 green packs.

I really don't know better, they won't tell how they do it.