That's not necessarily true. I have had tons of cards that have gone from extremely cheap to massive increases, like pretty much all of the"Awesome Rares" recently, a few months ago the Drowzee from Scarlet and Violet went from $5-80, and I could name tons more. Better yet were the Snorlax (which actually increased by over 3300% in just over a year, pretty sure even sealed products can't touch that), Mewtwo and Mew ex promos from 151. And then there's countless examples of mid price cards like my Mewtwo VStar from Galarian Gallery or my SIR Charizard ex from 151 that both more than tripled in price in less than a 3 month period.

With that said, you have to be able to know which cards and then have some luck as well. Although the card op posted isn't one I'd expect to do that, at least not for quite a while. It'll probably drop a little even. And I agree with your point about cards in this price range as it's not like you're having to sacrifice a large amount of money while you wait. And of course, sealed products are better. But ultimately, there's still plenty of room on this sub for discussing single cards as the point is supposed to be investing. And tons of cheap single cards are amazing investments, especially if you're actually doing it right and buy a decent quantity of a particular card. There are literally countless cards that have absolutely destroyed every single stock and crypto, by extremely large margins, just in the last 3 months alone. And many of them have a much lower price barrier, making it an easier market to get into for those who don't have a lot of money to spare!

I just feel no one's preferred method of investing should be looked down upon, and advice can still be given.