Eric actually had a number of offers over the years. I remember when Blackberry (and I think Apple, this was years back while we were in university and my memory is hazy) approached him (this was pre-production) to purchase Pebble for around USD 1 million and again afterwards. This was when it was just a sketched out product. He refused their offers and started making them out of his parents garage.
With the inflow of money into SV and ever growing valuations, perhaps he thought that valuations only move upwards.