[Nick Beale]

Apologies if I'm repeating myself but I think a useful approach is to ask yourself "Why wouldn't I write such a book?"

The list might include reasons like: lack of time, lack of sources, lack of confidence, never wrote anything of that length, not speaking a particular language, couldn't afford the necessary travel, didn't think many people would be interested and so on. And if those occur to you, there's a fair chance they've occurred to potential authors too.