I thought it was funny how when they first start working in the lab, Walt tells Jesse he's getting 1.5 million for 3 months. Jesse starts complaining that it's not enough because Gus is making 96 million dollars. Walt asks him, "Jesse you're now a millionaire and you're complaining?"
Then later on Jesse accepts a buyout for 5 million and Walt refuses saying it's not enough because of how he got out of Grey Matter too early.
Just thought it was funny how their perspectives about money and power flip-flopped each other.
It's all how they change as people, right? Jesse's at his darkest point, in terms of self-worth, when he complains about the cash. He's barely out of his rehab, Jane's died, he's angry and feels alone, and Walt's pushing him around. He feels hemmed in and he's really angry at Walt stomping all over him, so he goes after Gus.
Later, Jesse is in a better place, emotionally. He's matured a lot, he's made peace with a lot of things, and he's prioritised a bit better. The buyout seems fine because he's in control of his life. He can live with that.
Walt's got a problem not because of profits but because he doesn't want out ever. He wants to be the kingpin. He's actually way more interested in reputation than money. There's that famous "I'm in the Empire Business" line, of course, but also how bitter he is about Gray Matter.
And in the first scene with the lab, Walt was originally going to get 3 million from Gus. But when Walt demanded Jesse as a partner, Walt split it with him 1.5 million each. Just shows how he wasn't so greedy when it first started.
He also cared about Jesse. He did a lot of terrible things to the people he loved, but he still loved them. He wanted Jesse as a partner, he wanted him safe and looked after, so he was willing to split the cash. Again: it's not just money, it's rep. He liked his role as a provider and a protector and he wanted renown, even at great cost. So, his standing with Jesse was, I think, important to him.
Personally, I think Walt was always that greedy, he just had other things to balance that greed out - for the most part. His greed comes out quite a bit in S2 as well once Tuco's dead and he and Jesse start forming their own network. I think Walt demanding to Gus that Jesse be brought in as his partner and then sacrificing half his profits for it was more to do with Walt feeling he needed someone with him in that environment who was unquestionably in his own corner, who he thought he could depend on to back him up if it ever got into a sticky situation. Anyone else's loyalty would be split between Walt and Gus - Jesse was all Walt's. That's partly why Walt got so freaked out in S4 when Jesse started spending more and more time out with Mike and obeying Gus instead of him.
By S5, Walt no longer has to answer to anyone else and therefore doesn't feel the need to bargain with his profits, so the greed no longer has as much to balance it out since he no longer feels the threat of someone above him in the food chain. That and his reputation as Heisenberg the badass drug kingpin has evolved to mean a lot more to him as well. Both the money and the rep are basically their own forms of addiction to him at that point.