> You need more money, which means either higher taxes or more people earning taxable money. The speed of population growth is declining, which is a big problem

> You need more money, which means either higher taxes or more people earning taxable money. The speed of population growth is declining, which is a big problem for the latter, and the former clearly has its limits. What's worse is that a lot (most?) countries use exactly this model. Mandatory social security contributions are the reason why income tax percentages in many EU countries are so much higher than in the US. Look at https://stats.oecd.org/index.aspx?DataSetCode=TABLE_I4 https://stats.oecd.org/index.aspx?DataSetCode=TABLE_I4.