If 4 in 10 Americans are saying that then it's probably a pretty good indication that the Capitalism isn't working optimally for the labor classes.
In reality though it's a stupid poll or should I say the question of the poll is dumber than a bagful of hammers.
First, most Americans aren't exactly well read and don't know what the definition of socialism is.
Second, for much of our history our country has had no problem using Socialism when the free market fails to provide needed goods and services at reasonable cost. The Postal Service, The Military, Social Security, Public Education, Public Transportation, Public Utilities and Infrastructure, etc., all socialism.
The reverse has been seen too. Eventually the Free Market was able to provide cost effective postal services and as a result the US Postal Service has declined precipitately, as it should.
The point being though is if this polling # is correct and it continues to grow...then it would indicate that the Capitialist class is not sharing an equitable amount of the wealth produced by labor, with labor...but we already know that. One only has to look at the Champaign Glass graph of economic ineguality to see that. The stem of the glass can only be stretched so thin before it breaks with social unrest resulting.
All of those are paid for by private, capitalist enterprise tax dollars. Without that, none would exist.