What happens when too much power is given to one individual? Autocracy slowly and gradually creeps in.
Power should belong to the people as it is the people that is being governed. It is the people who elects principal officials into sensitive positions that can affect either positively or negatively. And that is why power isn't held by an individual. Russia may be considered as running a democracy cause they hold elections in which the people appear to have a say in who governs them but the actions of the present government tends to say otherwise. Laws are being put in place to silence and tighten the grip the government has on the general populace. The news media is heavily censored and citizens cannot have accurate news but propaganda that the government spreads in order to deceive the people.
Too much power shouldn't be in one individuals hand cause most likely, there would be misuse of that power.
Power corrupts but absolute power corrupts absolutely
Actually you must have heard that old saying that Opposition is the 4th pillar of democracy besides Parliament, Executive and Judiciary. If any of The 4 pillar is missing it can't really be called a democracy and this is really the situation of Russia right now, it has no genuine opposition in reality which is why Putin is continuing as a President for this long and this is why his powers are immense and he has no real threat to be overthrown.