How can precons be priced at approximately 50% of the total card value?

Since I’m fairly new to MTG I’ve been looking around for how I should best go about building my collection. When I looked up the collected singles price for a few different precon decks they were all about double.

How can that be?

Sure, I get that it’s a saturated market and getting the cards sold can be a hassle. But it’s still an asset with a retail price at 50% of its resold value.

I feel kinda dumb for buying a bunch of edh staple cards as singles, that I could’ve gotten in close to any precon.

Either way, I guess for someone in my shoes, who is starting out and don’t have foundational collection—precons are kinda goated.