The i8 is viewed more like a "tech gadget" than an exotic car. As many have pointed out, it's not a spacious car. People feel squeezed inside especially for Americans. The back seats are useless, and it's not even fully electric.
So in marketing terms, this product can be described as "stuck in the middle". It's neither here nor there. Nobody wants to blow $100k on a car that looks sporty but has no real exhaust note, can't even show off the engine (because it's so small), and it's not really "exotic car fast" - a BMW M2 can out accelerate it despite having all the electric gizmos. For the EV buyers, it's electric-only range is dismal, and does not support DC fast charge (probably because it has such a small drive battery).
In the real world, people can spend $40-60k (depending on model) on a brand new Tesla Model 3 that is fully electric with next generation motor and battery tech, out-accelerate the i8, is way more practical in passenger room and trunk space, and would only lose to the i8 in looks. And that's exactly what people are doing - which is why the Model 3 outsold BMW's, Merc's, Lexus's combined. So even if the i8 is considered "cheap" by your standards, very few people are buying it.