Many aspects come to mine there are a few that I wish to share with you about highlights I really like about model trains and the hobby itself:
You make great friends
There's always something new to do and explore on your layout
If you take your time and look around there are great bargains of something that you may have missed in the past but you want to include in your layout now
You can always learn from somebody who has been down that road and now knows how to do it correctly and passes that info on to others.
Always have plenty of Passenger and freight trains available to go out on the road