Big respect Steve!
You've earned it!
Commiserations on what must be a huge disappointment for you. A very tough decision to have to make. However, if you're ever tempted to think that you've let anyone down, please don't!
I don't think that's how anyone sees it and as a minor supporter I certainly don't.
Don't take anyone's musings on here or elsewhere about strategy or anything else as criticisms - it's just something people do with any sporting endeavour, and almost all sports fans are "armchair experts!"
I really don't think that anyone actually reckons they could have had a better stab at it than you have!
You've inspired a huge number of people to cycle more and further (and not just other HAMR contestants!) Lots of us have greatly enjoyed following your attempts too.
If, once you're fully recovered, you decide to make a 3rd attempt, I don't think there will be any shortage of support, and who knows - third time lucky?! It seems to me that you clearly have what it takes to break the record, you've just been really unfortunate. You'd have the benefit of a lot of knowledge and experience from your own and others' attempts. Edit: and likely no El Niño weather to contest with!
If you decide to move on to other challenges, you'll have left quite a legacy with the HAMR quite apart from your own record!
Enjoy the rest, and best wishes for the future!