Hard question to answer. Does the fetish bother your or impede upon your having a normal life? For some it may and in that instance, it might be best to forgo the activity. If it causes you not to be aroused in other situations with a partner, then it would be of a negative impact. A fetish isn't necessarily a bad thing but it does limit your partners that are interested in the same thing and you must always be respectful. Most people don't think their feet are being looked at sexually and you should never disrespect someone or make them uncomfortable with it when out in public. But if you can make it work as part of your life that it just is one aspect and isn't causing great social difficulty for you, then it's probably not harmful to indulge your fetish. But ya, I'd guess that the more you do indulge, the bigger of a thing in your life it will become.
I would say if you have a fetish & want to get rid of it, masturbating to that would NOT help you get over it, it would more likely reinforce it. Think about it - whatever we do, if we get pleasure from smthg, that’s the same as reinforcing that behavior. Instead, try to focus on the pleasurable feelings that come from stimulating yourself. You could try looking at OTHER stuff to help you get off, but then you could get hooked on that as well...
I don't think there is anything wrong with having a foot fetish as long as it doesn't become a controlling part of your life. I once knew a guy who married a woman based on her feet although he never told her that....that seemed a little extreme to me. But we all have our little fetishes in life. As long as you are not trying to cruise grocery stores or other public places perving on people's feet then I say just enjoy it!!