Nexus = new Citadel?

Sure - but the difference in scale of funding and resources is considerable.  I think also your other points are probably reasonable - especially the lack of profit point.  Bill Gates uses his money charitably latterly but he really is an exception most of the time. 

However, as I said I don't want to get into an argument about it.  I think the issue is that Bioware has decided it wants to write another Mass Effect story and has had to ... or perhaps has fallen into the trap of trying to - connect it to the original trilogy.  This means some kind of explanation of how it happened and the enormity of the task of travelling to another galaxy just doesn't work with what they had at the end of ME3.  I'd have been happier, tbh, if they'd just said that they wanted to write another story in the series but that it was a completely new story with no connection to the past.  Perhaps describing the events of a parallel universe which would allow them to have the same species, design and feel without having to account for Shepard or to cut Shepard out of the picture.  Alternatively, I'd have just about bought it, I think, if it had been originally an exploration initiative which was co-opted into an escape plan with the advent of the reapers and then they run for it and fall into a wormhole all the way to Andromeda but 'rich individuals putting together an exploration project just for the fun of it' just ... pft.  Not buying it.  In giving into the sentimentality of wanting to connect to the veracity of the original series, they created a problem for themselves.

It won't stop me buying and probably enjoying the game.  I loved MEMP and am looking forward to the new one (fingers crossed, double-crossed and tied in a large knot they don't bugger that up) and apart from the end of ME3, I loved the games themselves.  But my personal head canon is probably going to be 'in a parallel universe, the Hyperion's engines kicked into reverse and the long, slow deceleration began ...'