I want to start by quoting two sources that really struck home:
“I still love RM but the customer base is just too small to make a living from unless you are Terry.”
“Going hand and hand with that is the fact that for better or for worse the OSR is a thing. For the past decade and a half there been a group of hobbyists actively publishing, promoting, and playing classic editions of Dungeons and Dragon and similar RPGs. This is result of everybody taking advantage of the freedom granted by the open content found in the d20 SRD to expand the quantity and variety of material that supports classic D&D.” SOURCE.