Cards do not fail dramatically. They curve, they spot, and one day the surface has changed and nobody saw it happen.
What actually destroys them
Humidity. Cards absorb moisture, swell slightly and can stick inside a sleeve. In a monsoon this is weeks, not years.
Heat. A card in a hot room curves, and a curved card grades lower whatever else is true about it.
Light. Fading, worst on dark borders and on anything with a holo surface.
Pressure. A box packed too tightly presses the cards at the edges.
What to do instead
- Sleeved, then in a rigid holder or a proper box, stored upright rather than stacked flat under weight.
- Silica gel in the box, replaced when spent.
- Inside wall, off the floor, away from any window.
- Never a sealed bag long term — the same rule as everywhere: transit wants sealed, storage wants dry air.
Graded cards
A slab protects against bending and humidity far better than a sleeve. It does not protect against heat or sunlight, and a cracked slab is a damaged item even when the card is fine, so store them upright with something either side.
What it costs
Sleeves, a rigid box, silica. Less than one decent card for a whole collection, which is the arithmetic worth remembering.
Questions people ask
Should I double-sleeve?
For valuable cards, many collectors do. Make sure the inner sleeve is not trapping moisture.
Does a dehumidifier help?
In a serious collection in a coastal city, yes. For most people, silica and the right wall are enough.
What about the monsoon specifically?
Check at the start and at the end. Monsoon and your stock.
More: how cards are graded, packing cards.