At the end of the day - most of what makes a company valuable (or even functional) is the people who are working there.
Sometimes novel IP has value, and sometimes the company has assets that are worth something, but this is relatively rare for software companies.
If you are relatively popular with your current users, your brand may also have some worth, and quite a few companies are happy to scoop up a brand, hollow it out, and retire it a few years later once it's no longer associated with anything worth while.
Otherwise... The company dies, because it was not profitable enough, and this is both normal and expected.
