They sold 2 million units, which is nothing to sneeze at for a Kickstarter-funded project. What they miscalculated was the demand for the Pebble Time, for which they spent too much money on R&D and marketing to justify the results. They should have iterated on the original design, making it cheaper, smaller, and longer-lasting. Instead they tried to go upmarket and compete with the Apple Watch, with predictable results.