If you're doing it only to solve your own problems then why open source it?
Obviously, the motivation to help others, contribute to something as a community, show off your skills, etc. are drivers besides just solving your own problems. For some developers, solving their own problems has very little to do with why they work on open source projects.
Contributing to a community or showing off my skills would also fall under "solving my problems". It's perfectly logical to assume I may want better communities and recognition and the lack of either to be problems I may be inclined to solve.
So your original post is meaningless since you decried solving other peoples' problems... but solving other peoples' problems could completely fall under the set of "solving your problems".
"Is anything we do truly altruistic?" is a fun question philosophically, but makes for really circular/meaningless HN comments.
Obviously, the motivation to help others, contribute to something as a community, show off your skills, etc. are drivers besides just solving your own problems. For some developers, solving their own problems has very little to do with why they work on open source projects.