Magic: The Gathering Arena

Their bread and butter is gems. You need gems to buy the season pass, join some events like Sealed and to have a crack at some of their competitive events. The only way to get gems consistently is to Draft for them burning your Gold in the process, which requires a few hours at least per Draft and is most likely to not be a net gain in gems anyway.

As a TCG, they sell booster packs. Compared to other TCGs however, they also counted these packs towards the rewards in Draft and Sealed, which at least means you partially paid for these packs and not just for a chance at better rewards like in other games. Some events like Jump In only give you a random assortment of cards as a "reward", with no real reward for winning.

Arena uses a season pass.

They allow you to exchange gems for XP on the season pass. Some events can only be paid by gems and are basically paywalled. The most consistent way to gain gems is by spending gold in Drafts, which at best takes multiple drafts and at worst depletes you of your gems. Some of their value packages, however, are direct purchases. Getting gems and actual packs from their Starter or Explorer deals respectively. They also sell wildcards, their much more limiting version of dust, for money directly.

The paper version has a "salt score" for cards for a reason. Also some memes are based on toxic behaviour like roping or emote spam.

You need cards to build a deck at all and some Midweek events especially require odd cards, so you better hope you have those cards or some Wildcards to burn. At all times while deck building, if you see a card on screen, it will have a collapsible selection of multiple cosmetic versions of that card, where every card at least has an animation or 3d effect.

Cards are your bread and butter for being able to build a deck, so more is better. While there's no badges or achievements like in some games, there are limited available cosmetics and card backs.

Some events are heavily paywalled, where you can only use Gems and it's basically impossible to get multiple entries from converting gold to Gems from Drafts.

Depending on how lucky you are, Jump In might give you a deck that's much more powerful and consistent than the others. Due to how easy this makes winning your daily matches, this is the easiest way to pull ahead and complete your card collection. If you wanted to only play Constructed, then all your decks are limited by how many Wildcards you can get from boosters. Due to the way the game pays out, consistency is king, and consistency isn't free.

Arena developers stated themselves they wanted best-of-one mulligans to not give you 0 or 7 lands as often, so your opening hand is heavily skewed towards being more playable.