I know...there are smaller marketplaces that people can buy/sell goods via bitcoin, but why a major marketplace is not emerging??
I know for a fact, there is a huge demand for purchasing of goods with BTC...even users from this forum is enough to give the marketplace a supply chain issue

1. is the problem in supply side? are sellers worried taking payments via BTC bcas of volatility
2. is there a logistically inefficiency, that smaller sellers can never compete with the likes of amazon
3. is the transaction speed an issue for retail transactions?? major cards payments are done instantly (maybe this speed is needed for impulse purchases

)
Comment below...thanks i'm a newbie here

Soon my friend soon.
People just getting used to Bitcoin and cryptocurrencies. Soon we will be able to pay much more platforms with BTC.
There is no issue with your said. And yes transaction speed is important and we have to see some progress about block speed.