Yep people have all sorts of sources of motivations. One of the key ones is a sense of ownership. Many people join startups instead of BigCorp because they want voice and influence that they don't get in a larger company. I've seen so many founders, managers, leaders, etc kill that by not recognizing this fundamental fact.

Of course there's also the problem that you can find and hire people who are motivated people but there's absolutely no guarantee people are going to be motivated for your specific problem.