Most damage is not an accident, it is accumulation. Loose cards move, and movement is what causes soft corners and edge wear. Protection works as a ladder: each step solves a problem the one before it cannot.
Sleeve, case, binder. In that order.
Penny sleeve — Stops surface scratches. The cheapest thing you can do, and the one most collections skip.
Hard case — Stops bends and corner damage. A toploader turns a fragile card into a rigid object.
Binder — Stops both, and stops you losing track of what you own. Each step solves a problem the one before it cannot.
A shoebox is not storage
Loose cards move, and movement is what causes soft corners and edge wear. Most damage is not an accident — it is accumulation.
Four things worth checking before you buy any binder
Does it close when it is full?
Most binders are measured empty. The honest measurement is whether it still zips flat with every pocket loaded back to back.
Is it ringless?
Rings press into the cards nearest them. Over months that becomes a dented corner you did not notice happening.
Does the shell repel water?
Spills and weather at a show are the damage nobody plans for. The exterior is the only thing standing between them and the collection.