It's been a minute since I've seen it, so I don't remember the 1% royalty statement
But I thought he was just frustrated by the "No's" more than anything (whether true or not, IDK) To me, it seemed he was trying to get it to expand faster and faster (as a businessman) and the brothers were just wanting it to remain a nice "family" thing.
One of my favorite parts is toward the beginning when Kroc (Michael Keaton) goes up to the window to order his meal, they hand it to him in a bag and he's like "What's this? What do I do with this?" Although I'm WAAAAAAY to young to know/remember about the "drive ins" from back then, I just loved his portrayal of it. His frazzled/confused look of "WTF?!" lol
Another is when he's talking about the name of the restaurant and says something like "Who wants to come to 'Kroc's' restaurant?" or something like that. lol