I consider myself pretty skilled, but not on the same level as people who can pull off harder challenges (like the Hardcore mode you mentioned), or people who do challenge runs (RoahmMythril with his Mega Man Perfect Runs, or the speedrunners on Speed Demos Archive). I usually play just to finish the story, see if I like it enough to play through it again and unlock everything. Some of the stuff is really, really hard or tedious to get sometimes, so I usually don't bother with such things unless it's worthwhile in my eyes.
tl;dr I'm an "enthusiast," but not necessarily a "serious" gamer.