One of the main reasons many people are willing to put money in the game is because they not only anticipate being able to sell at some point, but they also believe card prices will hold up and even go higher. Without this belief, it just is not worth it knowing you most likely will lose money over time.
THIS!!!
I lost a shit ton of money on CHAOS cards. I thought my Riftwatchers cards would hold up better but they fell in value too. They focused so much on making Runi go up in value but most people's biggest holdings in this game is cards!
I would say that in a way it is fair to expect a loss on buying packs in the short run but if they don't have a way to over time make them retain at least around 50%+ of the original cost there are pretty much no expected earnings from the game. In the end, it all comes down to a combination of enough new people coming in and devs not flooding the supply like crazy which both aren't really happening.