To understand why the Bolsheviks failed achieve their idealistic goals, you need to look at the larger history of Marxism.

To start, in the mid-19th century Marx believed that capitalism has inherent contradictions that would lead to its weakening and being overthrown through violent workers revolution and replaced by communism, a utopia in which everyone would work together and the state would disappear. And he thought this would happen within a few decades.

But then decades went by and capitalism instead continued to grow, and this lead to a crisis in the Marxist movement. One faction, lead by Eduard Bernstein, decided revolution would never occur and decided to instead promote socialism through democratic elections and gradual reform. This group joined up with socialist democratic parties throughout Europe.

The other group, lead by Lenin, decided to double down on revolution. They thought the workers had been brainwashed and needed to be lead by a tight group of disciplined revolutionaries, a doctrine known as "vanguardism"

Lenin also believed that capitalism had escaped the consequences of its alleged internal contradictions by expanding to overseas markets through European imperialism. But he thought that this process had reached its limit and the result would be a world war, after which Europe would be ripe for communist revolution.

Finally, Lenin believed, contrary to conventional Marxism, that the peasants in agrarian, pre-industrial, pre-capitalist societies like Russia were naturally communal, and so it would be possible to go directly from feudalism to communism without having to pass through a capitalist phase.

Based on all these beliefs, Lenin lead the Bolsheviks in a successful takeover of Russia. The problem was that the communist revolutions in the rest of Europe never occurred, and so Russia found itself all alone and very vulnerable to its Western industrialized neighbors.

There followed a debate as to whether Russia should become a liberal capitalist and industrialize the traditional way,and eventually become socialist or push ahead with a dictatorial form of socialist industrialization. Stalin was initially for the first option, but after gaining power he switched to the second, with enormous brutality.

Then followed WWII, where the Soviet Union basically rescued the world from Fascism, and then Stalin's death, and a very dreary dictatorship that dragged on for decades until communism finally collapsed under Gorbachev.

In the meantime, a great many pre-industrialized countries, starting with China, were inspired by Marxism and the Soviet Union and also tried to move directly to socialism and then communism, and also failed. Even many nations that did not label themselves as communist, like much of the Middle East and Africa, still were inspired to follow authoritarian, semi-socialist paths. And all failed to achieve their goals.

Leftists say none of this matters because none of the nations were true communism. But in dozens of cases a group of smart and apparently sincere communists took power, and in every instance what they produced was not true communism, so the conclusion seems to be that true communism simply is not possible.