The problem with Jet for me is that it does the opposite of what I use Amazon for. I mostly use Amazon to order individual items as soon as I realize that I want/need it. Jet relies on ordering multiple things to bring the price down. Also, Amazon prime is so much more than a free shipping membership. It gives you access to movies, music and other things. I dont see how Jet or WMT or any other company is going to take a big bite out of Amazon's sales. And we dont really need a competitor for Amazon, we need (and have) competition on Amazon between sellers. That will keep the prices down.
The thing is that Jet usually has the same prices or lower than amazon before you add anything else to your cart.
Yes, Prime is more than free shipping, which IMHO is idiotic. Why up sell movies and music on a shipping service? These services have nothing in common. Nearly 50 million Americans already pay for Netflix, why should they pay again for Prime Video? $99 for free 2 day shipping is very expensive when you can get Walmart 2 day shipping for $50.
How about pantry items. Prime pantry is even more expensive, charging an extra $6 a box.
Walmart, pantry is included in the same price.
And we definitely want competition to Amazon. If other marketplaces continue to grow it will stop amazon from raising rates on sellers (who would in turn raise prices). And Amazon will need to continue to price competitively on the 50% of the items that they sell themselves. Also Amazon has lots of restricted categories, restricted products, suspended sellers.
On a lot of items they are not cheap at all.
TLDR; Diverse competition is always a good thing