seriously given such low monthly subscription, i wonder how much the sellers can make for the top up in terms of their profit margins
It’s similar to the situation where an item is sold at its recommended retail price (RRP).
The seller can still make sales, but the upstream distributor needs to take a cut in order to secure their share of the market.
For typical retail products, smaller sellers may drop below the RRP to boost sales.
However, that doesn’t apply to this product.
On top of that, selling online comes with high commission fees.
As a result, the effective discount can easily reach perhaps 30% off retail. (if seller want to protect their 10% margin "guess")
Online commissions alone range from about 10%+ to nearly 20%.