I created a CMS that did user integration with message boards, there were few to none at the time.
I made many mistakes, the biggest ones were:
1) Having hit a relatively high success at 21, I felt indestructible. I had no fear of spending most of my income on entertainment. I knew nothing about budgeting, I should have saved.
2) Towards the end, I definitely spent too much time having fun and ignoring the product. When you're on a high roll for so many years, you feel invincible.
The decline started gradually, but in my mind I always believed I could easily bring everything back on top. At the end, I repeatedly did everything in my power to save the product but it was too late.