The Madagascar that megaladapis would have lived in was much different from today. It would have rubbed shoulders with all manner of strange lemurs, dwarf hippos, giant carnivorous fossas, and other long gone creatures. Megaladapis' forest specialization made it vulnerable to changes in its environment. When early humans arrived on Madagascar 2,000 years ago and began clearing the forests for farmland, the koala lemurs lost much of the habitat. The remaining giant lemurs were hunted to extinction only about 500 years ago. This is why we can't have nice things.
The extinction of the megaladapis was recent enough for them to live on in cultural heritage and oral traditions of the Malagasy people. In fact, the first western culture ever heard about these giant lemurs was from local legends about colossal wild beasts with strange, hauntingly human faces. Of course, megaladapis didn't have a remotely-human like face. It's pig-like skull and eyes that didn't face entirely forward would've been dead giveaways. It is believed that the local legends of the many different extinct lemurs got merged together over time into a creature with the size of the koala lemur and the face of its slightly smaller, more traditional primate cousins.
Today in parts of southern Madagascar, people occasionally report strange sightings of mystery creatures resembling large, man-sized lemurs. Does megaladapis or one of its fossil cousins live on? Cryptozoologists seem to think so, but lets be honest it doesn't really take much to get them going does it? Bless them.