I don't grind for anything, but I can see why it's so much more draining to grind in this game than others.
For Trade, you have to keep doing "repetitive" tasks like jumping from sometimes multiple systems to multiple systems just to make maximum profit. This can get tedious if you're not doing it for fun and only for the end result. With no fast travel system like other games, you having to make the same distance trek every time can get tiring.
For Combat, the TTK (time to kill) anything is wayyyy slower than any TTK in any other game. Look at a game like Halo, then look at ED. Even grinding in MMOs is faster. The slow pace just to get, if you're lucky, another 1% on your rank, when you're trying to get to that Elite status...it would be frustrating for me, anyways.
For Exploration, if you're not in it for the sights and experience, doing the same jump/fuel scoop/scan for hours and hours, days on days, weeks on weeks, and sometimes months on months...I mean, it drives the people who are INTO it crazy. Imagine what it does for those not into it?
That's why I've done a little bit of everything. Conflict Zones, RES/Nav Beacons, 8k-from-the-bubble trip, Rare trading, smuggling, mining... some things I prefer more than others, but I do my best to not let something get stale. If it starts feeling like work, I try something else.
For rank, though...I got a good chunk of my rank before the BB was nerfed to oblivion. If I made it my mission to get to something like King, as they are now, I'd probably tear my very blue hairs out.
Any time I find someone commit to something, like maxing Imperial or Federation ranks, or getting Elite in something, or just setting some kind of crazy personal milestone, I feel a sense of admiration to keep at one specific task for so long.