This theory would only be found to be true if indeed there were no "rich" left in the country by, say, 1977, after at least a couple of decades of high rates of income tax for high earners.

Truth was that there was a wave of moaning and wailing from the "rich" and threats of "I'll go abroad" but when push came to shove and the wife asked "Where will we be emigrating to then dear", the bravado faded with the realisation that emigrating to a country with low or no tax would probably destroy their social and family lives.

Moral of the story is to tell anyone who repeats the moan "I'll go abroad if they tax me at 50%" to go ahead, sell the house and take the family somewhere cheaper, go on, do it now...they won't.

Do you also find self loathing therapeutic as well as despising individuals less fortunate than yourself?

You mean running their own business?

You said people should get off their backsides and do something to change their situation.
Does that include working together with others to improve many peoples working lives?

Where is the like button?

The thing is, if all these people "got off their backsides, and achieved" then the world would essentially grind to a halt. Who would stack the shelves in the supermarket? Who would load the luggage on to the planes at the airport? Who would process the invoices for all the "achievers"?
What would happen if developing commodity exporting countries, and the workers within those countries working for peanuts because they don't feel they have another choice suddenly realised that they're being bent over, and actually started charging a more appropriate price for their labour, commodities?

The fact is, big business needs a significant amount of unskilled labour to pick from to exploit. It needs a high level of poverty, and corruption in developing countries to keep their import costs down.
Governments need people on welfare to buy votes. Big business needs government, to be able the pass legislation that favours their interests.
There're are definitely people in society who are parasites, and exploit the system, but many of those people are the ones who designed the system in the first place.