Why Communism/Socialism/Democratic Socialism is a disaster

Historically, all this started with Karl Marx, a writer back in the mid 19th century, say 1850 or so.  In those days, and on continental Europe especially, there was a serious discrepancy in wealth.  The workers got little, the owners, capitalists, got a whole bunch more than the workers.  Marx felt this was unfair.  His solution was to share the wealth equally.  The state would own all the means of production, from steel mills, railroads and farmland, down to corner bodegas and restaurants.  The state would set equal wages for all.  Marx wrote all these ideas in his book "Das Kapital" which was widely read. 
   The messy part of Marx's plan is how the state obtains owner ship of nearly everything.  The owners resisted this idea strongly.  In Russia it took a massive social revolution in 1917 to bring this about.  Owners, kulaks the Russians called them, were liquidated.   Massive propaganda efforts and a powerful secret police were used to overcome resistance of kulaks.  Kulaks, entrepeneurs, who escaped liquidation fled the country.  Taking their ideas and initiative with them.
   Production sinks under socialism because the highly motivated entrepreneurs are gone.  Since every one gets paid the same, nobody is motivated to work hard, since there is no reward for hard work.  Starting a new business is forbidden by law.  You can see this in Soviet Russia, even today, 30 years after the fall of communism.  You can see it today in Venezuela.  "They pretend to pay us, we pretend to work" was a cliche from Soviet times. 
   The only real difference between Communism and Socialism back in the day, was how the party would obtain power.  Communists believe they should obtain power by revolution and force of arms.  Socialist believe they should obtain power thru political action and the ballot box.  Once in power there is little difference between them.
  Modern "Democratic Socialism" is mostly undefined, especially by its advocates, say Bernie Saunders, Alexandria Ocasia-Cortez, and Elizabeth Warren and their followers.  The followers are looking to a regime of more free stuff, and the leaders are looking for political power.  Elizabeth Warren was talking about the federal government taking over all of big business, which sounds pretty Marxian to me.