" I think it was Margaret Thatcher that said..in as many words..."the problem with socialism is..sooner or later you run out of other peoples money ". That is actually an excellent definition of capitalism. LOL
Democratic Socialism in various forms works well in a number of Countries, often the Government is a Coalition, so not fully Democratic Socialist. But if the U.S were to consider such a Government, or the U.K, or anywhere, to achieve it would mean a system of Proportional Representation, Single Transferable Vote perhaps, but there are other systems.
Why consider Democratic Socialism ? just look at Portugal, a very poor Country of the E.U. but as soon as they got rid of their Right Wing Austerity wielding Government things have improved immensely, many who had left the Country in disgust at Capitalism unfettered extracting money for the 1%, but investing little in the Country, have started to return. Things are looking up there, just with a change to a weak Democratic Socialism.
For the US and the U.K to achieve a Government " For The Many, Not The Few", which is what D.S is, both Countries would need a new, real, Green Democratic Socialist Party to emerge, and for P.R to be brought in. In the U.S the Republicans and Democrats must go, in the U.K, the Conservatives and the Labour Party must go.