I already explained how significantly the rich contribute to society in
this post.
Without the wealth creators, there is no economic activity. Without economic activity, there are no jobs. Without jobs, there is no tax revenue.
It all starts at the top. The billionaires of the world may not be paying large amounts of direct taxes but the tax revenue they generate makes up a huge proportion of the total tax take.
The 80/20 rule is certainly applicable in the Singapore context.
In reality ...
The rich are not always wealth creators. Just look at rich PAP politicians who are more like parasites
You mention indirect taxes, but conveniently forgot tax arbitrage.
Many large companies produce goods and services that cost roughly the same as those without economies of scale. The reason why they are able to sell cheaper is to outsource to a cheaper country. As a result, They employ less or no staff and contribute less taxes to the communities that they are serving.
Also, large companies are known to destroy wealth by nipping budding competition through dodgy patent lawsuits, dumping, predatory pricing, etc
There are also too much croyism in capitalism that ensure that wealth is re-distributed from the poor to the the rich. You can tell from the amount of VC capital that is used to fund risk-taking entrepreneurs compare to the cosy government handling out juicy deals to preferred powerful friends /companies or erecting unfair laws disadvantaging the rest.
That is why we have countries suffering from Dutch's Diease, working poor, McJobs, US car workers cannot even afford the mass-produced cars and there are evidence of the poor getting poorer while the rich get richer. If the rich are creating so many jobs and generating so much revenues, everyone should have better living standard.