MMOs aren't money sinks. Look at World of Warcraft, look at Lineage.
Bad MMOs are money sinks.
Bad anythings are money sinks.
Bad MMOs are money sinks.
Bad anythings are money sinks.
By comparison, you can launch a social game for five/six figures in two months, your primary acquisition method will be virality backed up by cross-promotions and FB ads, if it doesn't work you shoot it in the head and do another one, and if it does work you double-down on development and quintuple-down on advertising and then print money hats.
I think Age Of Conan was an interesting case, launched with big publicity and was quiet good. Things outside the introductory areas though weren't fully fleshed out and there were some big bugs. In the first couple of months they lost most of the user base, one you start a decline in an MMO network effects take hold.
They have put an extraordinary amount of work into the game since this point, building a great game, and had success with the free to play model. Still though, the biggest impact on where they are now was these first few weeks.
That's not true, and its falsity is a very important idea. Making mistakes less costly is often a better strategy than trying to avoid them.
It seems that saying one out of ten MMOs do well would be generous.