People attach greater value to things they have made themselves than if the very same product was produced by someone else. This cognitive bias is known as the IKEA effect.
Creating something yourself boosts people’s feelings of pride and competence, and has the added effect of showing off their competence to others. This can lead to an overly subjective view of a project.
Chandler: [Rips his jacket on the large wooden tv unit.] Wow! That ripped! That ripped real nice!
Joey: How many times I have to tell you! You, turn and slide! You know, turn and slide.
Chandler: Oh you don’t turn and slide, you throw it out! I’m tired of having to get a tetanus shot every time I get dressed!
Joey: Well, we’re not throwing it out! I built this thing with my own hands!
– Friends (1997) Season 4, Episode 2; “The One with the Cat” [No. 75]