Affiliates are at the bottom of the food chain.
As affiliate, you can be a giant specimen (making lots of money), but you are still just a prey to the ones above you.
Shit, I constantly see affiliates targeting my sites and promoting various offers through the Adsense units I run. And if I see one ad that doesn't disappear in a few weeks -- which probably means it's profitable -- guess what happens?
I add that domain to my competitive ad filter, and then set up my own creative or banner for that offer and rotate it in place of the Adsense unit some percentage of displays.
So the bottom-feeders end up first paying me money to do market research for me, and then if they are successful I simply separate them from my audience and take over.
Get out of the aff marketing while you can. You need to control the audience. If you can't do that, then control the product (that's second best). But if you control neither, then you are just a glorified hustler. And sooner or later you'll get tired of hustling.
Don't get me wrong. I'm not saying affiliates can't make it big. But what you should be thinking is how to use your current affiliate income to become something else other than being an affiliate.
Whoever controls the audience is at the top of the food chain. Product owners/service providers come next and form a symbiotic relationship with those who control the audience. And "pure" affiliates (as in don't own the audience and don't own the offer) are nothing more than short-lived scavengers.
Sticking in affiliate marketing for long is like first becoming a stripper "just to pay for college", and then turning into a crack whore some years later.
Do what you need to do to make money now, but don't plan the rest of your life according to what your current campaigns make you.