The silver decade of Luxembourg is a time when the country went from rags to riches. Luxembourg wasn’t always wealthy. Like most countries, they begin poor. Usually, they have just attained their independence after a war. Wars cost money, so they had to spend a lot of money to get their freedom. Then they start to set up their economy. It usually takes a lot of time to get the economy stable and growing.
Once it grows, then the country can become rich. Luxembourg became rich due to the steel industry with one company in particular. It is ArcelorMittal, but the steel industry has been around in Luxembourg long before this company was founded. Then Luxembourg began establishing banks and other financial institutions which grew their wealth.