To understand a person, it helps to consider what the world was like when the person was twenty years old. At twenty, give or take five years, the music of the day, the politics of the day, the language, mores, fashions, economic conditions and whatnot of the day make a very deep impression. It is an impression that lasts through life and functions as a sort of benchmark for the evaluation of what comes after, but also as a distorting lens that makes it difficult for the person to see what is happening now.
The foregoing insight may help us understand why people remain in the Democrat Party. People born in the 'twenties are many of them still living in the 'forties. For them the Democrat Party is the party of FDR. They haven't noticed the changes, or haven't wanted to notice the changes. They haven't noticed that their interests are no longer served by the party of this name. Or perhaps they are just attached to the label, or in the grip of misplaced piety: they are attached to a family tradition. "My pappy was a Democrat and my grandpappy afore him was a Democrat; we McCoy's have always been Democrats, and we don't see no reason to change now."
People born in the early 'forties are many of them still living in the early 'sixties, those heady days of Camelot when the young and vigorous Jack Kennedy and his charming wife occupied the White House, and society was all in a ferment with necessary reforms being made or about to be made. They thrilled to Bob Dylan's "Blowin' in the Wind" and other anthems of the Civil Rights movement. Those worthy battles were fought, and they were won, and progress was made. Jim Crow bit the dust. The liberals of those days can take pride in their accomplishments.
But soon enough the rot set in: the legitimate struggle for civil rights gave way to affirmative action as we now know it, which involves reverse discrimination, race-norming, preferential hiring, and minority set-asides. Martin Luther King, Jr. was soon followed by such race-hustlers as Jesse Jackson and Al Sharpton who cleverly cashed in on white liberal guilt. People were precisely not judged by "the content of their character" but by the color of their skin. Equality of opportunity was confused with equality of outcome; the quota mentality replaced the concern for justice. Justice gave way to the unconcept 'social justice' which either means nothing or is code for socialism. If you believe hiring should be based on merit you are now called a racist. Liberals transmogrified into leftists whose calling card was and remains the race card. 'Racist' and 'white supremacist' became all-purpose smear words used even by presidential candidate Hillary Clinton.
In the '60s , Democrats were progressive and liberal in respectable senses of these terms. But it is no longer the 'sixties, and if JFK were alive today and held the views he held then, he would be classed with conservatives. If you are living in the past, however, fixated on the glory days of youth, you may have missed the changes. You may not have noticed the difference between Jack and Teddy, the difference a brother can make.
So if you are still a Dem, you need to ask yourself: Are you living in the past? When the Dems become indistinguishable from the CPUSA will you still call yourself a Dem?