That's part of it, but not everything. In the 2020 presidential primary the number one issue for everyone, including seniors, was electability. Beating Trump was what Democratic voters cared about, and cable news blared the false but believable message that only a centrist who could capture Republican votes could do that.
Another big issue is, oddly enough, minority voters. Minorities are not all that different from other populations in their policy views, but they do tend to be far more committed to the team blue. (Though that commitment is waning). That means that minority conservatives tend to vote in Democratic primaries, giving us more conservative Democratic nominations.
I really wish more people would vote on something other than their own perceived self interest. Barring that dream, we need to fix broken perceptions. The people seniors and others are voting for, in both primaries and general elections, don't actually serve the interests of their voters.