Gold with credit cards

I regularly buy gold wby applying credit card discounts on amazon/ flipkart. After discounts they are either less than or nearly equal to gold current price (without gst, making charges, etc). It's a great deal, helps with accumulating gold + meet spend based waiver or lounge benefits + milestones + reward points if applicable. Great option for investment using credit cards.

Did anyone else try doing this? What are your thoughts?

P.s.: please don't say invest in stocks/MF etc because I'm doing that also, and I'd anyways need gold in few years for jewelry, etc where I can exchange these coins...I can keep accumulating smaller coins, so not get hit with huge sudden expenditure.