If you’re genuinely saddened that you might not make money from some photographs you took on your iPhone 4 two years ago on a free photography social network you still freely enjoy now, then yes, please close your account. But, for the rest of us, welcome to the very nature of modern business.
A company needs to make money. You took your pictures so that you could share them with the world, and you weren’t expecting to make any money from it. Seriously, chillax.
While I’m on the topic of Instagram: making fun of people who take pictures of their meals isn’t clever. That joke got old pretty much the first time anyone heard it. Posting that joke on a social network just makes you sound like a hypocritical ass.