I had no idea where you came up with the "150,000 copies" figure but then I ended up seeing the same thing listed on a page about "More Effective C++", which ha

I had no idea where you came up with the "150,000 copies" figure but then I ended up seeing the same thing listed on a page about "More Effective C++", which has been in print for 2 decades. Even if he received $3-4 per copy sold for all those books, that's over a 20 year timespan, that only works out to $20k or so a year, although he does have other books. It's possible that Scott Meyers might be a sufficiently popular author to be able to support himself just on book income at a level comparable to having a decent day job, but at best it's a very close thing and even so he would be one of the extremely rare few who could do so.