A great deal of thought has gone into this concern over the centuries. The "Rights of Man" declared during the French Revolution set a goal of equality of opportunity, but not equality of ability.
From the Declaration of the Rights of Man and of the Citizen, set by France's National Constituent Assembly in 1789, is a human civil rights document from the French Revolution.
Article 6: All the citizens, being equal in its eyes, are equally admissible to all public dignities, places, and employments, according to their capacity and without distinction other than that of their virtues and of their talents.
One could say that even the die-hard Marxists would agree (somewhat)
"From each according to his ability, to each according to his needs" is a slogan popularized by Karl Marx in his 1875 Critique of the Gotha Program.
Perhaps even the Marxist ideal above is not promising a comfortable lifestyle to all, but only "to his needs...". So what is the minimum a person "needs" in a Marxist society? A basic ration of food staples and a collective roof over one's head. The impression I have today is that our current crop of would-be socialists translate this as everyone getting a luxury spa lifestyle, while partying and sleeping 10 hours a day, because, well... equality. I have good friends that struggled to get here from places like Cuba, China and the USSR, and they are some of the strongest opponents of this false promise.