I'd hardly call embedded work an extremely small niche. Now, what he's doing on them may or may not be. But microcontrollers on the whole are a much bigger industry than personal computing. You'll find many more 8-bit and 16-bit microcontrollers in any given house than you will Intel or AMD 32/64 bit general purpose microprocessors. Last I checked approximately half of all CPUs sold globally were 8-bit.