That's a very narrow-minded way of looking at success. The success of a state is much more than just attaining wealth — it's about serving the people and giving them all possible opportunities to pursue their dreams and live a happy life. Money is just a means to be able to carry out these tasks.

And there are enough statistics out there to prove that money is far from leading the list of things that matter most to the happiness of humans.

PS: (And in a country with as many immigrants as Singapore, I'm sure the issue of foreign languages is self solving :-)

The three ethnic groups in Singapore get in touch with each other quite well, that's true, but contact with any other culture such as European ones is rare (expats just stay amongst themselves). Furthermore, learning a language requires more than just knowing native speakers.