This is Le Mutant (The Mutant, 1978), a French sci-fi mini-series.
Wikipedia has the bit about decreasing violence. Translated from French:
The various nations of the world have decided to make peace and destroy their weapons, while society's control over all activities through video surveillance is increasing. A mysterious scientist leads this pacifist movement through these Peace Legions. But the apparition of a Mutant, endowed with powers that go beyond nature, will call everything into question.
Further, this forum has the bits about the chip and the guy aging. The "Maison" you remember is probably the name Masson, the professor Masson and his son Saül Masson being key characters of the series. Again, translated:
The story follows a reporter investigating people behaving weirdly. She meets an odd guy who will only eat tiny green cubes of an unknown food. And he takes control of people by putting a weird thing in their necks. At the end, he tells the journalist he enslaved the whole world through a TV recording, because he died prematurely, and she ends up being the only "normal" person, watching the mind-controlled people on the screens... [...]
A fascinating, horrifying sci-fi series where an organization attempts to uncover who is Saül Masson, son of the rich Professor Masson. A strange blond teenager who only eats an equally strange green cube, all while from the top of his tower, an old man (whom we will only see the scrawny hand of, laying on his armchair) spends his time watching TV screens, seemingly monitoring everything...
Various screenshots and newspaper articles can be seen here. All six episodes are on YouTube, in French. Below is the sixth and final one, with two very relevant timestamps:
I found it by remembering a very similar question I answered a couple months back: 70s TV miniseries: antagonist gets followers to his pacifist ideology through mind control devices.