Why the Madoff Ponzi scheme was not sustainable for an unlimited period of?

Another reason Madoff managed to fly under the radar for so long (despite multiple reports to the SEC about suspicions of a Ponzi scheme) is because Madoff was a well-versed and active member of the financial industry. He started his own market-maker firm in 1960 and helped launch the Nasdaq stock market.

Explanation:

Many pyramid schemes will claim that their product is selling like hot cakes. ... Yet, both pyramid and Ponzi schemes are illegal because they inevitably must fall apart. No program can recruit new members forever. Every pyramid or Ponzi scheme collapses because it cannot expand beyond the size of the earth's population.

Explanation:

the underground railroad (apocope of the metropolitan railroad) is a system of urban trains located within a city and its metropolitan area. it is characterized for being a massive transport of passengers in the big cities, uniting diverse zones and their environs, with high capacity and frequency and in segregated form to other systems of transport. metropolitan railroads are built underground or on the surface, although most systems use mixed models where sections are combined in both modalities.

1 - as a result, the metro tends to reduce car travel for two reasons: first, due to the greater transfer of users from the car and, second, due to the reduction in the acquisition of cars in homes located in sectors near the stations of the metro.

2 -the metro allows to contribute effectively to the achievement of all the objectives of an urban development policy: it improves the efficiency of the city's economy by reducing travel costs and also generates a higher level of activities in the city center, taking advantage of of the agglomeration economies.

3 -it is a clean means of transport, since it uses renewable energy (usually electricity), taking care of the environment and avoiding excessive pollution.