1) First one was an ISP, boot-strapped. 4 years. Mildly profitable, sold to a larger ISP.
2) The next one was a short stint with a e-retailer. They were almost immediately profitable, but needed some serious cash to grow. So it sold within a couple of years and the founders all still work there. It's wildly profitable now, but alas none of the founders can capitalize on that success outside of a steady job.
3) Next one was a NLP middle-ware company (yes, they exist) that had been around for more than a decade, I came in near the end and worked there for 3 years. It sold right after I left (I didn't have equity). I believe it was unprofitable.
4) After a few years bouncing around mega-corporations I came back to startup land. We're 4 years in. Just hit profitability this year and then the Congressional funding disaster hit (we're almost entirely government business). We're going to see if we can make it through, but we may end up selling.
5) My wife and I just launched our new company www.kymalabs.com (her main job, my part-time job). We'll see how long that goes! We'd actually like it to grow enough to pay our bills and give us long-term employment, but who knows!