I presume one reason could be at 40 you dont make the mistakes you made at 20. I was 20 once and when i built a product i tried to load it with features/options. Now at 30 i make things as simple as possible. I don’t discuss which DB to use. I straight away use SQL. I don’t discuss scaling issues. I dont bother about 80% of the issues i used to discuss when i was 20. I’m better of now.