[misja111]

Long before he turned senile, he turned corrupt. He has ruined his country economically.

This is the real reason for a maximum of 2 or 3 terms. Power corrupts.

[badminton1]

Also when a regime has been involved in crime, they need to perpetuate themselves in power to avoid prosecution.

[rb666]

It's recently been proven you only need 1 year for this.

[mathw]

In the case I think you're thinking of, the corruption was pre-existing.

[kbart]

"This is the real reason for a maximum of 2 or 3 terms. Power corrupts."

It's still easy to be gamed, see Putin-Medvedev-Putin switch.