Good question! I feel like my answer to that is mostly around the fact that I enjoy new challenges and working on new things. Most of the time, I stay for just a year or two, do amazing work, then move on to the next problem. Typically not at the fault of the startup. Though some of the things I look for when joining a new one is if it's aligned with my own personal values and if I think the work I will be doing will be enjoyable and I have the ownership of it.

Though all that said, I think consulting now is a great middle ground for me since I can do what I love about having new challenges without the bad feeling of leaving in what some would consider a "short" amount of time.