I think the majority of people who make discoveries which could be profitable do hold that information back until they amass stock of the item in question. There’s nothing wrong with that, but it can be seen as a bit shady if done on a large scale.
I personally don’t tend to keep information I’ve uncovered private unless it’s something I’m interested in collecting which would otherwise be difficult to do if lots of people found out. As an example, I made sure to have almost all of the Japanese 2001 barcode pack variants before I started sharing information about them outside of a few small Discord groups: www.elitefourum.com/t/guide-to-early-pokemon-tcg-history-1995-test-card-versions/31779/28. I didn’t withhold this information for profit though, rather because the packs themselves appear very infrequently and I knew if a lot of people were going after them it’d be impossible for me to do so, especially where booster packs aren’t at all a primary collection of mine.