Very lucid comment. I would just object to your harsh "it's irrational and probably stupid..." final remark.
It's not irrational and stupid. Building something allows you to sharpen your skills, validate your abilities, engage you to the problem you want to solve for real.
cheers
Sometimes one pretends to build the thing for someone else, when its first and foremost for oneself. That can be a bit irrational but also often unnecessary - there is nothing wrong with making something for oneself.
