I don't think that the large commissions is a problem that something can be fix by your idea. First off all the commissions handed down by the ecommerce platform is not always fixed most of the ti.e before even a reseller sales its items to the platform they will always enter into a negotiation first. So I really do think having an Amazon version 2.0 for you won't change anything. Another thing is you need to have loads of cash to even steal a market share and resellers from e-commerce giants. You need to have a better idea than this one.
I think the idea of just stealing from you is the market for cryptocurrency payments would be a start.
I'm going to make a demo of the project. I think they are this would give a clearer idea to the points I mentioned. For the truth it is difficult to expose an idea only in text. Visually, it would be better.

Not really, the thing is we have a e-commerce website who is accepting Bitcoin and its name is
Overstock, have you seen it overtaking Amazon or Alibababa and getting their market shares? We all know the answer and its a big NO, accepting cryptocurrencies as a payment method will just look like an option for a lot of people and the thing is they will always go to the popular ones with wide selection instead of just going to a website who just accept cryptocurrencies. Like I said you need to be realistic here as your project seems to need a lot of capital.
But theres nothing wrong if he would continue to proceed on the things or into those ideas on his mind but atleast we do give examples to those e-commerce website that
do already imply/applied the idea he's been thinking.He would realized if he would tend to check it out.

It is a lot easier for Amazon to add crypto payments than it is for you to build what they have.
Thats the hardest part on how do you get a marketshare when you see on what kind of competition you are tending to dive in.