Because it's a 76% increase in price?So, why get the SA100 when the ~$130 Topping MX3 is a mini all-in-one (including headphone out) with better power amp measurements (similar wattage with better SINAD)?
This is a great data point to show another obvious (that most people don't realize), that a brand doesn't mean much in terms of performance. SMSL can make stunning equipment, but just because it's an SMSL, it doesn't mean it is going to have great performance. This applies to just about everything else in the consumer market. Yet, people buy brands.
I think many economic theories really need to be re-done; any theories that assume humans make "rational" decisions are totally wrong.