Do The Older Generations Actually Understand What Socialism Is?
Yeah, we do.
There are two definitions of Socialism, one economic, the other ideological:
1) a political and economic theory of social organisation which advocates that the means of production, distribution, and exchange should be owned or regulated by the community as a whole.
2) (in Marxist theory) a transitional social state between the overthrow of capitalism and the realisation of Communism.
These don't actually contradict each other, and both imply a centrally planned economy with no free market capitalism. What Millennials fail to understand is that Socialism as an economic system is completely unworkable: it has been tried in Eastern Europe, the USSR, China, Vietnam and Cambodia: It always fails, always leads to economic collapse. If you want more modern examples, try North Korea, Zimbabwe or Venezuela. The only thing Socialism is successful at is creating a flow of refugees fleeing the Socialist order.
All that you can guarantee is that after the Revolution a ruthless dictatorship is required to enforce Socialism, and that Central Planning is a fallacy: it can't be done.
Socialism is a pleasant-sounding fantasy of equality and brotherhood, but rhetoric is all that it is. Marxist theory is designed to inspire young fools into destroying their own society in a glorious Revolution, but all it will do is replace elected leaders with brutal killers.
Because Capitalism is the only known economic system for generating new wealth, it is important that we keep it: it has lifted 5 billion people out of extreme poverty in the last 30 years, so it must be protected.
Economic models have no moral dimension; that is what Law is for. If a Capitalist breaks the Law, sue or prosecute him. Capitalism is ethically neutral: it is just the free exchange between a willing seller and a willing buyer. If you have issues with injustice in society, you address that through Politics and the Justice system, not by attacking the economic system which makes us all wealthier than any past generation has ever been.
Socialism does not and can not work: the best you of the Left can hope for is a little more welfare state to protect the weakest members of society, but not at the cost of deincentivising small businesses, confiscating earned wealth, and undermining or repressing the capitalist free market. You must be careful not to over-regulate the free market lest you kill the goose that lays the golden eggs!
I suspect it is you who don't understand what Socialism really is: "If you are not a Socialist at 18, you have no heart. If you are still a Socialist at 28 you have no brain!" ~Winston Churchill