There is a simple way to test the "they got lucky" hypothesis - look at their combined cumulative career profits since the Market Wizards books were published.
If you add up the combined profits, they are much higher than what you would expect from a random selection of traders, let alone a randomly selected proportion of the population in any field of human endeavour. And this is including the ones who "blew up", had poor results, stopped trading/retired, found their edge went away etc.
So, someone selected a number of traders with excellent track records, who then gave clear explanations of definite methods they used to make money (some of which, especially in the last book, were obviously purely down to a once in a lifetime bull market existing). There is still the possibility of survivorship bias. Then, *after* the books were published, i.e. on a forward-looking experiment with no survivorship bias whatsoever, the Market Wizards make a collective net profit in the tens of billions.
Anyone who calls that luck might want to take a refresher course in logic and statistical inference.
As for Buffett, he is 20-30 years older than most of the "Wizards". Compound $1 billion at 14% for 30 years, and you get $50 billion. And remember that most trading markets, at that kind of size, become illiquid, so favour Buffett's long-term hold + corporate takeovers + insurance sales over short-term speculation; the tax system also has a big bias in favour over investing vs trading. But if any of the better Wizards, like Druckenmiller, Cohen, PTJ, Kovner etc wanted to keep on trading and investing professionally for 30 years, rather than retiring and enjoying the good life, then I'm sure they could manage a 14% return on their investments.
P.S. regarding traders' edge disappearing - this is easily demonstrated by looking at, for example, mutual fund timers and time zone arbitrageurs (now there are industry-wide high switching costs, and the activity is borderline illegal), or floor traders (electronic trading removed their execution speed and information-flow edge). In each case there are specifically identifiable reasons why they had superior risk/adjusted returns. Those reasons then disappeared - thus their method no longer worked. That's a pretty open and shut case IMO.
