I'm not dismissing your idea, but the fact you managed to purchase a 3090 on launch day seems more like survivorship bias than anything else.
On the other hand, I did get a 1080ti several months after launch during the crypto-boom of 2017 using the same approach. I have also stumbled upon lots of "we added more tickets to X event" type situations before they are announced on social media and disappear in an instant (think sold out music festivals and concerts).