Thats why I said $100m should work. You suggest $65m. That's the same order of magnitude. It was reported that the VCs were turning them down because $1B was "never gonna happen"[1]. That's why the math piqued my interest. If its just reporting hyperbole...that would be one explanation.
[1] Which implies they were looking for that extra ~order of magnitude
If they went up to, say, a Series B at 10M and a Series C at 20M, which are reasonably conservative multiples, they are at ~36.5M, so looking for a ~400M exit. It's not hard to need that ~1B exit if your business plan is "everyone in the world using my product," and it appears this is what Everpix were aiming for.
It's pretty common for A-round investors to be diluted by 50%. http://www.bothsidesofthetable.com/2011/10/14/understanding-... shows it pretty well.
It takes a roughly constant amount of time to do a deal, so funds have a minimum deal size below which they aren't interested.