The hobby can crash in a handful of ways, its not 100% risk free.

One day for absolutely no reason at all Pokemon could just start putting chase cards into box products a few months after release and completely tank their values which would have a trickle effect into sealed. As the expensive chase cards that justify their value no longer sustain their value.

The Pokemon company could cut out distribution and resellers and lgs and become a more straight to consumer seller. This would choke how distribution or resellers hold large amounts of product from consumers and demand more money for it.

Print to oblivion, new facilities, just 24/7 churning out product. Facilities dedicated to older product. Each week sees a new set reprint on shelves at big box or something.

Its not impossible for collapse. Its not precedented or likely. But not impossible for pokemon to go full konami and reprint to the ground.

Heck pokemon could even sell master sets as a product.

Nothing is impossible