Japan, Korea and a lot of European countries don't have natural resources. Plus, they are bigger in land area with a much bigger population thus the administrative duties in those countries are far more difficult in nature. Some of these countries are susceptible to natural disasters too.
Try asking LHL or LW to be the president of a country like U.S, SG is like slightly bigger than half the size of NY for your information.
Anyway, the British left behind a well-working infrastructure and a legal/civil system which the government built on. SG was not a fishing village when they left.
We were the most important of the Straits Settlements and already
established as a thriving entrepot for regional trade by the mid-nineteenth century. When the British handed over control, they left behind Southeast Asia's leading port, a naval base, several airfields, and the accumulated soft and hard infrastructure from over a century of settlement
https://www.lowyinstitute.org/the-interpreter/singapore-50-time-s-fishing-village-narrative
Our importance as a strategic location at the southernmost tip of the Malay Peninsula particular at the Straits of Malacca, at a critical crossroads of trade between Asia and Europe meant that we were blessed with a geographical advantage.
Hong Kong, Macau, Shanghai, Rotterdam, Los Angeles and Tokyo are also similar to Singapore in that regards thus no surprise that all these areas also have a high trading volume due to their ports, thus leading to high GDP for all of them respectively.
Not discrediting the success by the early PAP (1G leaders like LKY, Goh Keng Swee, Toh Chin Chye, S Rajaratnam, Ong Teng Cheong and Devan Nair, etc.) supported by a robust civil service at that point (like Tommy Koh and Ngiam Tow Dong, etc.).
But if you think the current PAP of the last 10-20 years are still the same as those, you are greatly mistaken.
Why did you think TCB said that PAP has lost its way?
Why do you see the likes of Tommy Koh and so many people who used to work in Civil Service/Stat Boards/GLCs like Tan Suee Chieh, etc. speaking out against PAP?
You cannot confuse the current 4G leaders with the 1G leaders' success, there is only how long they can ride on the coattails of those who laid the foundation/blueprint, everyone who is sensible knows that the 4G leaders simply are nowhere close to being competent as the original 1G leaders.
Toh Chin Chye was anti-PAP in his last days for your information.