Complaining you don't get free stuff anymore is really unbecoming of an entrepreneur.
He wasn't complaining about that. He was led to believe that the price would be reasonable, and he was willing to pay a reasonable price, as he already pays Imgur.
It seems the OP has a very distorted impression of what "reasonable" means to another for-profit company.
Only Reddit knows how much money it loses per user who doesn't see ads.
Prices are a two-way street. You can name any price you like, but if buyers can't afford it, then you make $0.
This is why the developer himself can't just raise his own prices by any arbitrary amount. Buyers have some say in the price.
Indeed, but this is the risk in selling a middleware product. The Apollo developer doesn't own the platform, and was lucky he hadn't yet been asked to pay for the share of maintenance costs his app created.