For Kickstarter to continue to function, most projects need to deliver what the backer originally wanted - this, in a way, represents an ROI since (presumably)

For Kickstarter to continue to function, most projects need to deliver what the backer originally wanted - this, in a way, represents an ROI since (presumably) the product of the campaign was worth more to the backer than the amount they spent. There are of course a whole tier of backers that get stickers or just thanks for backing projects at lower tiers - these backers are altruists who believe that the project is worthwhile without expecting compensation.