Wow, Erlaya, beat me to the punch. Posting this anyway since I spent too much time on it.
Changes in value happens in EVERY TCG. Wizards bans a card = value decreases massively. New combo comes out with an ancient card = value rises drastically. Card rotates out = massive drop in value. Balance changes are just our equivalent of these types of changes in value.
In TCGs with ever-growing card pools, card values do indeed change all the time. However, there are subtle differences between these types of changes.
Bannings are typically the most ugly changes, as it's basically the developers admitting to players "Well, we screwed up." Bannings typically cause card values to plummet, harming players who devoted their resources to obtaining them. Even though bannings should be expected as a possibility, it still seems like a breach of trust, or at least a great disservice to the game's involved supporters.
New combos coming out actually has a pretty positive effect on games. It rewards players who see potential in underused cards, who bet that something just doesn't have the right support, that something is waiting to be unlocked by a future addition. It generates new creative deckbuilding space without adding as much new content.
Card rotations are healthy for competitive environments, but also can have effects on card values, especially on cards that excel in Standard but hold no traction in eternal formats. However, these devaluings are easily anticipated with rotation calendars being available, allowing savvy players to unload on their money cards before rotation, and allowing poverty casual players to pick up these cards after rotation at discounted prices.
Balance changes are kind of a recent concept in this age of digital card games (at least to me, anyway), but they seem more akin to bannings than to any of the other changes. Whereas cards can be reevaluated by players or have their time in the limelight run out, them being altered has more of the "we screwed up" vibe to it, with the unsavory investor experiences mentioned prior.
CAVEAT: This is a beta. Investing real money in beta games, where your products are still subject to drastic, unpredictable changes, has been historically risky.
DOUBLE CAVEAT: This is a game made by humans. Cool, but fallible humans. Since Lightmare seems to know what they're doing, I'm sure they will do everything possible to not screw up once they get out of beta. But when (not if) they do, the methods they use to deal with their failures will help define how they treat their community, and in turn, will decide how secure people feel their invested time and money will be.