I want to know the answer to the following question:
What significantly increased the magnates wealth?
All the background I'm provided with is that "Often, those gifts were only temporary leases, which the magnates never returned (in the 16th century, the anti-magnate opposition among szlachta was known as the ruch egzekucji praw—movement for execution of the laws—which demanded that all such possessions are returned to their proper owner, the king).". Is that enough to answer the question?
Answer: no