It wasn't Ike that. People are misinterpreting Walt being in his feelings about Grey Matter with bitterness towards Gretchen and Elliot. These are his FRIENDS, not two people who screwed him over. Walt was still cool with both of them years and years after whatever went down went down. They loved Walt, which is why they offered to basically pay for his medical bills. Walt's whole thing with Grey Matter is Bitterness born of REGRET not bitterness born of scorn. Gretchen even reminded him "You left ME". Walt's entire conversation with Jesse was about why he didn't want to let go of the Heisenberg Empire, because this was his second chance at building something great and sticking with it, seeing it through to completion, believing in himself and his own genius.
Nah man. Walt said "something happened between the 3 of us", so whatever happened with Gretchen obviously involves Elliot too. I find it hard to believe dude randomly left his girl for no reason, and then, at the same time, totally unrelated to that had another problem with Elliot.
And Walt hadn't spoken to Gretchen and Elliot for years prior to that party in season 1, ep 5. He said "these people aren't even in our lives any more". They wasn't friends or cool with each other.
I'm sure he does regret taking the buy out but he flat out accused them of getting rich off his work in "Peekaboo" in season 2. So nah it's not as simple as "he left the company, and regrets it". If that was the case he wouldn't have reacted the way he did at the end of "Granite State".
Fred.