> And you had to be very greedy indeed to convince yourself that 20% interest is a safe investment

I think there is more nuance that this. People have been burned by many 'safe' investments over the years (housing, stocks) that they incorrectly view the risk profile as similar so look for higher returns. Much has been written on how we under appreciate actual risk, especially in 'safe' investments.

There's also some YOLO here, but in a calculated way. A safe investment making 1% still means the wealth gap is widening and that person is still eating ramen. Why not swing for the fences, otherwise it doesn't matter anyway.