Is Splinterlands pay to win?

I've heard some people claim that Splinterlands, a popular blockchain-based trading card game, has a pay-to-win element. As a cryptocurrency and finance professional, I'm curious to know if there's any truth to this. Could you explain the mechanics of the game and how much, if at all, does spending money give players an unfair advantage over those who don't? It's important to understand the implications of such a system for both the players and the overall health of the game's economy.