My worst day in eve was circa 2005/6. I was out ratting in our home region (dek) in my raven with a lot of blue fitted. At the time, that raven was worth about 3x everything else I owned. (mistake number 1)
On my way home from ratting, I decided to run just a few more belts, and as a result, got caught by a couple of interceptors and a vagabond. They tackled me and began pecking away. Anytime I got any damage on one, they would bounce of a nearby planet and I'd have to start all over again.
So I called for help in corp chat, but most of my corp wasn't around at that time of day. So I called for help in alliance chat, 347 members logged in. NOT ONE SINGLE RESPONSE. I kept trying, and for over an hour and half, I asked (begged) for help, and despite being 3 jumps from VFK (our primary staging) got no help what so ever, not even a "tough luck kid". Eventually they got the raven into armor, and of course it melted in seconds. I warped my pod out and got it back home safely, only to see 130 people in local, many of them active.
So I lost a raven worth nearly a billion isk, back when a billion isk was a big fucking deal, and found out that my corp and alliance didn't give two shits about me.
So I promptly loaded everything I owned into a badger and made a burn for highsec. I made it unscouted (surprisingly) and docked in .5 space. Where I dropped corp, and promptly cancelled my sub. It was over a year before I came back.
By this time, my old corp had shifted rather substantially, and we were part of MM living in tribute, so I decided to try it again. Mistake number 2. Being that my play time was late US TZ only, I was never included in anything. I hardly ever managed to get to CTAs or strat ops, and when I couldn't make it, my corp set taxes to 100% so that ratting (my only income) was pointless. After some time being a third wheel, I started pulling all the third wheel people together and doing harassment roams. This lead to me getting noticed by the people up top, and finally getting some traction in the corp/alliance, which was actually way more gratifying than I care to admit.
The worst day of my eve life was being in IRON and being a peon. The best day of my life was being in MM and being tapped to run dark ops and spai.
I'm still in that corp, but now I'm in leadership and help run day to day operations, while we plan for the future. Rich as fuck, I welp 1+ billion isk ships for fun and laugh at past me being upset about a measly raven.