said this back on page 299. looks like I mite be gettin my wish
The problem is you're falsely assuming Elliott stole Gretchen and pushed him out. We weren't given any indications of that and an interview with the actress who plays Gretchen contradicts that idea. Walt felt insecure because Gretchen came from money and Walt left her. Walt wasn't pushed out. He was just too weak and insecure at the time to deal with it and stay with his company. Walt took the buyout and sold his potential for 5 grand.
Now... Elliott and Gretchen distancing themselves and ignoring Walt's impact on their company, that's different. It's a smart move on their part from a business standpoint, but Walt naturally takes it as an insult.