I doubt there is 750000+ hardcore raiders in wow. Just go to wowprogress and take the top 4000 10man guilds and top 1500 25man guilds. Let's assume every 10man guild has 16 dedicated raiders and every 25man guild has 37 which is already very f***ing generous.
Now let's add that up.
(4000 x 16) + (1500 x 37) = 119500
and I strongly doubt that there are 4000 10man guild world wide you can consider hardcore raiding guilds, in fact the world 4000 10man right now has 4/14 normal which is less than my alt has done in pugs, and there are only 1296 25man guilds listed at all having killed a single 25man boss in SoO.
Considering wow still has a subscription base of I assume bordering 8 million, heck why not say 6 million.
119500 / 6000000 x 100 = 1.992%
and as said, those "hardcore" guilds i counted are mostly far from hardcore and I doubt every 10 man guild has 16 active raiders and neither does every 25man guild have 37 raiders, 12 players benched per night
The more realistic number for "hardcore" or rather heroic raiders, lies somewhere between 0,7-1% of the total subscription base, imo.
Face it, we hardcore raiders, are a VAST minority.