Why was the next generation of a big family not as good as the previous generation?

Actually, this had a lot to do with the environment they lived in.

The older generation was born into a humble life. They had to earn their own money to pay for each of their own meals, and they worked hard to earn every single cent they spent. So, during that time, the people who were able to build up a family business would never be considered mediocre. They were all regarded as elites.

However, after they h