Is the Shopee $1 big prize worth trying out? Technically I get cashback in Shopee coins so it's not a waste of money? Is it?

Personally I don’t buy it. If you buy it, you would give yourself the excuse to spend the coins. Given that coins can only form max 30% of the total purchase. So you are actually unnecessarily spending $3+ for every $1 you “invest” (that’s how they get you to spend!). Unless you are going to buy the stuff regardless there is this $1 prize event or not, then sure go ahead i guess?

Yeah. If you are a frequent shopee user like me. You should just try since 100 coins is $1 rebate you can redeem for next purchase. Regarding the chances, it is definitely low given the amount of people who use it.