Drug dealing, arms trading, David Tweed's share trading, offers, Peter Foster's slimming tea, trading property debenture "investments",
Sure drug dealing is generally illegal (except alcohol of course), but are all of the above really creating a "benefit to the country and society"
Our economy is a service-based economy. Most of these are things we could do ourselves, but these days we choose to pay someone else to do it. In that respect, trading is no different - liquidity for a fee. If trading is not seen as beneficial, then consistency would require the same opinion of most jobs. In this perspective, the only jobs that really provide a service are the ones we can't learn to do ourselves (ones that require deep and focused education).
Another point of view is that trading has been around since early society, so it is obviously a necessary service. Very few jobs can claim to be have played as significant a role in society.
Wayne's post is spot on.