Well, let's just do the math: the original pro version has over 100,000 downloads over it's 10 years of life. At $3, that means the dev earn at least $300,000 over 10 years, minus 30% play store fee. Let's say they earn at least $27,000 per year, which is almost twice the minimum wage at the very least.

Now lets do the math for Lemmy version: some metrics say we have 1 million users. Let's assume 10% of them are active users (100,000), and among those active users, lets assume 10% of them (10,000) buy Sync for Lemmy at $3 (the original price) one time purchase (a very generous estimate). This means the dev will get $27,000 (after 30% cut from play store) from those users, ever. Even more likely is only less than 1% of active users buy it, which means the dev would earn something like $3000. Even if they sell it for $20 it's likely they still won't earn the same amount as the old Reddit version.

So yeah, I don't think the dev is greedy. In fact, I'm concerned that they won't get enough money to earn their living and we'll all have to go back to Jerboa (it's good though, but not as good as sync).