I've printed and sold comics, so I guess there's "success" in that, but I'm not where I want to be right now. I'm not disappointed, coz I know the indie comics game is a long one; like @LordVincent stated, it's a matter of just being consistent and staying patient. For me, making my own comics IS the end game; if I could sell merch of my IP, then that is a bonus, but I want to be successful making my own comics.
Just like others, I'm happy every time I get a new subscriber or see a comment on a page I've worked so hard on; it lets me know that there are people out there that LIKE/love what I do. It gives me incentive to keep doing what I'm doing...