Clear, readable, up-to-date documentation is also a 'secret weapon' in another scenario: when you want people to adopt your software and use it. It doesn't matt

Clear, readable, up-to-date documentation is also a 'secret weapon' in another scenario: when you want people to adopt your software and use it. It doesn't matter whether you're selling to businesses or promoting an open source project - good quality documentation is the exception not the rule (even from large multi-million dollar companies). You may think the program operation or the code you wrote is self-explanatory, but there will be dozens, hundreds, maybe even thousands of users who will never email or contact you to tell you they're struggling with your software. They'll just give up and silently go elsewhere.