M
Mr D
Social democracy - welfare statism, workplace democracy, still capitalist (Bernie Danders fits here)
Democratic socialism - social dem + conscious anti-capitalist "democratic" move to replace capitalism
Socialism - workers own the means of production, revolution of the proletariat, democratized workplace
Communism - socialism + abolishment of the state, abolishment of private property
Saying a social Democrat is one day going to turn into a communist is about the equivalent of saying most capitalist economies around the world will eventually become fascist.
It does nothing to address humans being easily corruptible.
Being a lifelong union member has taught me that giving even the most well meaning people power results in the same problems in a capitalist system when people gain power.
People have to run and lead whatever system you think is better.