Disclosure: I worked for various "startup" companies starting in 1991 through 2005. One got bought by a large company and made me some money, but not a life-changing amount. Some others variously went into "zombie" mode. One got bought by a company that simply milks the existing customer base for support revenue. One failed outright.

That said, when the first company was bought, there was a product that the buying company didn't want to continue to support. Some friends of mine made an agreement to take over that product, and started a company to do so. They never grew the customer base that much - it was a niche product. However, they were able to continue to work together as friends, have decent paychecks with 100% company-paid insurance, and after about 15 years, sold out to a company for enough to allow for comfortable (not rich) retirements. This was all on purpose and was discussed frequently by them - "Do we want to grow, or do we want to enjoy what we're doing, have some free time, less stress, and remain friends?"

I've always thought that was a FINE model for a company, if you can pull it off. I always wanted to work there (did some consulting for them), but they could never grow quite enough to hire me. Ah, well. :)