Most failed stores are not badly built — they are built for a niche that never had room for a new entrant at that price point.
Score four things
Demand you can verify, margin after all fees and shipping, competition you can differentiate from, and fulfilment complexity you can actually manage.
Avoid the traps
Fragile products, heavy items, tight regulation and categories dominated by a single brand with deep ad budgets.
Validate before you commit
A small test order, a landing page and a modest ad spend will tell you more than another week of research.
