Also it's generally a very bad idea to try to build your own decks from scratch if you want to be competitive. Although things shift far more often (due to new sets and rotating formats), competitive Magic is similar to chess in that you're better off studying and mastering known-good decks, since very few people can reliably outperform the ruthlessly honed decks produced by the worldwide competitive community.
And yes, we spent our fair share reading up and talking to other players about their meta decks, that in itself is great fun also, just of a different kind.
Compare to, say, Hearthstone, where the digital cards have zero resale value, but the up front cost is substantially lower.
Standard is the most popular format, and has the lowest power level of the major constructed formats. Cards are only legal in standard for about 1 year. Most cards that are played in standard aren't powerful enough for Modern, Legacy, or Vintage, so once they rotate out of standard, their value drops.
Siege Rhino, for instance, lost 80% of its peak value by the time it rotated out in April.
https://www.mtggoldfish.com/price/Khans+of+Tarkir/Siege+Rhin...
Modern is funny. It's non-rotating, but has a fairly aggressive ban list. No big deal if you play casually, but it's possible to drop $1-2k on a T1 deck, only to have a key card banned a year or two later, or for the meta to shift and your deck to be hated out of the format.
Legacy, Vintage, and EDH are generally more stable.
By the time I've opened all the product I generally have copies of most of the set's staple rares and I can trade or sell anything I do not need.
It is a sizeable chunk of cash upfront if you specifically want to play constructed you can acquire 'singles' in pieces and build towards a deck over the season that way. I do not play standard at all. I'm a big eternal format fan (especially Legacy). Once you acquire those cards you can play with them forever.
One thing I have noticed is a lot of eternal format cards are getting thrown into supplemental sets (i.e True Name Nemesis, Shardless Agent, Council's Judgement, Containment Priest, Dack Fayden) stuff like that. Which tends to spike the price.
I think I might start trying to be the organizer more, it might just be that everyone is waiting to be asked :)
I like to do this too