I think a better comparison would be... a community art gallery opens, they invite all local artists to show their work for free. It becomes more popular then the Louvre and the owner gets fabulously rich, and sells the gallery to MOMA.
One day the new owner of the gallery realizes it's losing tons of money (and taking visitors from it's money making gallery in NYC), and it knows the artists are not going to pay (and maybe can't afford to). So it starts making prints of the artwork and selling them without giving the artists a royalty.
The whole idea of instagram was "instant postcards". The idea that they would help you do make these. Not that they would go creep out shots of your family and sell them for a profit to 3rd parties without consent. Or sell your data to be analyzed and fed into behaviroual profiling for junk mail. If they want to charge for postcards, then nobody would complain in this way.
Instagram is (now) just a clever form of social engineering...not a product.
One day the new owner of the gallery realizes it's losing tons of money (and taking visitors from it's money making gallery in NYC), and it knows the artists are not going to pay (and maybe can't afford to). So it starts making prints of the artwork and selling them without giving the artists a royalty.