“And maybe there’s a way to do that better”
And that is?
“And maybe there’s a way to do that better”
And that is?
You are kind of proving their point here. You are trying to reason with them, but in your mind they are not being reasonable, so you are disengaging because you don’t see how further engagement can be useful. Instead, you just call them the bad one.
This is exactly the process you are arguing against. People are not being reasonable, so you can’t expect reason to be convincing.

Yes, a better candidate would be ideal, and that should absolutely be pushed for in the primaries. What is your plan to help that?
But everyone’s idea of an ideal candidate is different. If the Democrats don’t field a candidate you like in the general, what will you do? Will you withhold your vote, and in so doing help the party that is actively damaging the country win? What is your plan?
We can sit here all day and complain about this side or that side and how the Democrats are failing, but in the end that means NOTHING without a plan to DO something about it.
What is it your are going to DO?
That depend entirely on what that “something else” is. So far, all I’ve heard is either “don’t vote unless the candidate is ‘left enough’,” a vague and counter-productive inaction; or various calls to “tear down the system” with no indication of a plan how or what to replace it with.
I’m not saying the Democrats are faultless, but empowering the people that are proactively causing harm doesn’t help.