The way I see it, you now buy packs for 4$ (eventually the DEC should be worth that) which gives you 5 cards most likely 4 commons & 1 Rare. Old cards range from 2.5$-10$ for a max level card which has 400 limited copies combined. Once Modern cards are dumped into wild, their utility is almost fully stripped away and they are bound to trade closer to the value of the cheapest cards. I would be surprised if it was possible to out-earn the devaluation over their time in modern which is why I believe it' a losing proposition.
When it comes down to the price, you never really know. I used to think under 0.02$ for SPS was a really cheap yet here we are 66% lower. The main thing I look at is the likelyhood that Splinterlands will keep existing. In that regard, I see Splinterlands as probably the #1 best Crypto game out there.
Now I understand why you said a player is losing money in modern.