Psychologically minimalism is based on the idea that happiness doesn't come from stuff but rather from relationships and experiences. So when you get rid of the excess stuff surrounding you, you can better identify those things that are really important to you and what brings you pleasure in your life.
Studies have shown that people who are more focused on worldly pursuits, like getting rich and buying stuff, are at higher risk of becoming unhappy, anxious, having low self-esteem, and even developing problems with intimacy.
You may find yourself less stressed and more focused once you're living in a clean, organized space. Having fewer things to worry about really can make life seem more manageable, from the practical chores you do on a day-to-day basis to the big projects and problems you face.
When there is less chaos outside, we're likely to feel less confusion on the inside.