The timeline of the campaign makes it pretty clear that either:

1) they knew they were insolvent, and wouldn’t be able to continue

or

2) the campaign was used to demonstrate market demand to enable their sale to Fitbit

Edit: also, they sold for $23 million [1], total pledges were for about $13 million, and not everyone got a refund [2]

[1] https://www.businessinsider.com/fitbit-bought-pebble-for-23-...

[2] https://www.kickstarter.com/projects/getpebble/pebble-2-time...