This.
I myself had a forum until yesterday lol
It was MYBB based. My focus was Money Making. Firstly I was busy doing all the hardword and runarounds to make it famous and out there. Then when I when I was in the middle of it there came the leechers. Posting just thank you and copy pasting. Soon I lost interest in managing it and also I aint no 16 here I am 27 with love and a kid to take care now. So I passed and moved on.
Short: Use your energy/time and money on forums only if you think you take it long.
