When we got acquired, I assumed that I would leave as soon as I could and do it all again - but yet, I'm still here. It's interesting work, and while I miss the ability to just get things done, I find that I've been getting a lot better at dealing with problems at scale. So, for example, how DO you launch a new product to a sales and support organization with hundreds of people?
I'm not saying I'll never start a company again, because I really want to, but I'm enjoying feeling like I'm learning how to do things better next time.