It is hard not to be jealous of other people's successes, and maybe it ought to be hard. The act of fighting that feeling teaches us something we might not have garnered any other way.
Sitting here, counting on my fingers, I count one, two, three people I know on a first-name basis who I could consider successful authors. One of them is successful enough in comics that most everyone who has read a major A-list comics title in the last decade ought to recognize the name; another contributes regularly to the book publishing component of a major entertainment franchise that's a household name. A third is not a household name, but even that person's level of success is something I envy.
I never held any jealousy-as-malice for these folks — the feeling that somehow they didn't deserve their success, or that it could somehow be karmically transferred to me if they were laid low. None of that. They deserve to be where they are by dint of the time they put in, the connections they cultivated, the sweat and blood said work drained out of them.
What I did have was something potentially worse, something I had to discipline myself out of: the sense that only by growing close to those people and partaking of their success in some way would I ever have any of my own. That it was only through the success of others that I could find any.
There are innumerable reasons why this is wrong, but I'll focus on a few key ones. First, and I think most crucial, is how such thinking stunts your own spiritual growth as a creator. You're not really thinking about what you can achieve on your own, but merely how you can siphon off a little of someone else's mojo for yourself. It becomes most dangerous if the other person does in fact give you a little of what you ask for... and then you inevitably discover it's not enough, and you're even more disappointed and resentful than before. The other guy waved his magic wand, but there you are, still a frog.
At the bottom of this is an ugly feeling I suspect a lot of people don't even know they have, the urge to find someone else to take responsibility for their problems. If you nag a friend for a leg up, and he gives it to you only to have nothing happen, you can blame him instead of yourself. You can pretend it was his fault because he didn't try hard enough (even if you have no idea what he did or didn't do), because you deserve better (even if you really don't, especially if you're not taking control of things that are supposed to be yours anyway), because ... you get the idea.
One of the tougher concepts in Buddhism that has been lifted out of it and made into a pop homily is the idea that a bad thing can be a good thing — that every challenge is actually an opportunity. The profounder (and wormier) truth is that it also means good things are bad things, that success brings with it the risk of complacency, that being handed something means not learning how to earn it.* And under that is something tougher yet — the idea that this dualism is something you can only find out on your own, the hard way, from the inside. Reading about it in books will not help you.
The only way you learn about your own jealousy is by being jealous, recognizing that for what it is, and knowing better. It teaches you something you don't get any other way.
* Note that I am not making this point as a prelude to advocating a policy, because I think these are things that have to be discovered on one's own, not enforced from the top down; they're only effective when they come from the inside.