Pre-Sales of Boxes/Cases - How sellers get their hands on cards before a release

Saintbeastie

I just recently got back into the hobby (last was in around 1998) so I'm trying to catch up on a lot of information. One thing I noticed today is that it's very difficult to get ahold of boxes at cost on any manufacturer's website (Topps, Panini, etc.). Today I tried to secure a box of 2020-21 Panini NBA Hoops and I was unsuccessful. I went on the website several minutes before the boxes released, had logged in, payments were setup, and the sale started at 8am PST on the dot. As soon as it went on sale, I hit "Add to cart" and I got hit with an error that there was too high traffic and to retry. I sat for about 15 minutes continually trying and was unsuccessful; they eventually sold out.

I then went on eBay to look at the boxes and to my surprise several people had already purchased and received their boxes before the item even went on sale. I'm curious how people had already purchased and received their boxes before the product was even listed on Panini's website. Any idea how people purchase these in advance and how I could do so on either Panini or Topps products?

I know Topps has a members club that allows some limited pre-sales, but I see places like Steelcitycollectibles pre-selling HUGE quantities of these releases before they come out, and always are able to get their hands on them. Is there a wholesale membership with these companies that I'm missing?