The letter writers do it all. But the biggest pay off is through IPOs. Letter writers are given opportunity to buy stock during the private company stage, or on the initial offering.
Example: in British Columbia, company X can sell private shares to 50 investors who must certify that they qualify as residents of the province. These shares are generally sold at about 25 - 50 cents to fund the corporate startup.
So, letter writer out of province gets a friend in the province to buy the shares (one case went to court last year) or, alternatively, keeps an apartment in the province to establish an address. The regulators seldom check to see if this is a legal resident so the scam is easy to pull off.
Letter writer buys 50,000 - 100,000 shares of cheap stock for, at max, C$32,500. Company goes public and letter writer publishes big, bullish story on same. Stock goes to several dollars on bullish story and while you are buying, writer quietly sells his 25 - 50 cent stock to you for, say C$2.50/share, or about C$250,000. In a bull market letter writer does this for, say, 5 companies each year. Quick C$1.25 million reported as US income to qualify for low US taxes.
He then asks you to pay him big bucks for his special edition service so you can get the hot tips first. Offer valid only to first x hundred takers at US$X,000 per. Another US$X00,000 per year.
Also gets great trips to world's exotic spots with stop offs at fine beaches, good skiing, etc. Great business, built on the back of investors' greed.
As a former Mining Securities Analyst and corporate IR person, I've taken a number of writers to exploration sites. Only one would know a mine from a barren hole in the ground.
In the 1800s it was called Mining the Eastern Stope (investors's pockets).