Hopefully, when you turned down the job offer, you did so in a classy way. As a hiring manager, if a candidate I extended an offer to, reach back out to me after declining, and said their situation changed, I would consider making a new offer. True you lose negotiating leverage, but I would expect a percentage greater than 0 of companies that would re-engage with you.
> Told my friends/family about the job, and that I will be moving to America
This is a minor issue. Plans change. They'll get over it. Hopefully they didn't throw you a going-away party yet :)
> Reached out to all my contacts (including everyone who was trying to hire me) and attempted to sign them up for this YC service
No good deed goes unpunished. But seriously, you did the right thing by trying to help out this company. I don't see this as a problem.
> I reached out to several people (e.g. at Google, FB, Partners at a management consultancy (i.e. my former employers)) asking them for a potential investment into this company ("Use our personal networks" was a key strategy), some of these helped me find a job that I turned down
I'm sure those same potential investors will circle back around to you, and decline investing, given that you are no longer with the company.
Hopefully, when you turned down the job offer, you did so in a classy way. As a hiring manager, if a candidate I extended an offer to, reach back out to me after declining, and said their situation changed, I would consider making a new offer. True you lose negotiating leverage, but I would expect a percentage greater than 0 of companies that would re-engage with you.
> Told my friends/family about the job, and that I will be moving to America
This is a minor issue. Plans change. They'll get over it. Hopefully they didn't throw you a going-away party yet :)
> Reached out to all my contacts (including everyone who was trying to hire me) and attempted to sign them up for this YC service
No good deed goes unpunished. But seriously, you did the right thing by trying to help out this company. I don't see this as a problem.
> I reached out to several people (e.g. at Google, FB, Partners at a management consultancy (i.e. my former employers)) asking them for a potential investment into this company ("Use our personal networks" was a key strategy), some of these helped me find a job that I turned down
I'm sure those same potential investors will circle back around to you, and decline investing, given that you are no longer with the company.