A layout is like a dynamic work of art. Visiting it, tinkering with it, just being in the presence of it, can generate good feelings of satisfaction and accomplishment, and to admire its beauty.
What I find really cool is that we model railroaders see beauty in things others can't see: a weathered locomotive on an industrial siding, a long string of oil tanker cars or coal cars (especially if we can smell the oil or coal) pulled by a GG1, ballast between the rails and railroad ties, weeds and trash along a right of way, etc.
I remember taking a walk with my son (when he was 13) and he was mortified when I started filling my pockets with tiny pebbles, just the right size to be ballast for my traditional O Gauge Lionel track. Fortunately, no one saw us so he wasn't too embarrassed.
A train layout can also be therapeutic, even medicinal, spiritual, and vital for our well being.
I remember seeing a train video with an elderly model railroader. He had lost his wife and may have been a retired physician. He explained that building his layout with the help of his friends after losing his wife was tremendously beneficial to him. What I remember about his layout was a steam boat moving up a river, and an early 50s NY Central F3 diesel (A-B-A) pulling many train cars along the river.
For me, the trains have given me great relief (a heavenly escape) at times, especially in the past, when my career as a lawyer was most stressful. My layout has been a man cave to mull things over before talking about them. It has been a place for creativity, and to connect with the child within. It has been a place to experience and remember good times with parents, with young and adult children, with grandchildren, and with friends.