The only way to sustain an economy indefinitely is through equal trade of goods and services. Jim the carpenter fixes John the farmers roof, and John gives Jim food.
Any form of economy built on profit will crash. We do not have unlimited money or resources. We can substitute some services for money (as we clearly do,) but it’s the for profit part that destroys everything.
This is vastly oversimplifying things, but at the root of the matter, there’s only so many M&Ms in the bowl, and people getting greedy are taking the candy from people who haven’t even reached the bowl yet. Then those people with a surplus are trading their M&Ms for Skittles and marking them up for everyone else