First of all, the bolded part is pure bullshit. Making the best of the choices you have is called being an adult, not representing the worse of anything.
Secondly, do some of their ideas filter in? Sure. But in exchange, you're handing the keys over to the other party which often takes things in the exact opposite direction of where you want to go.
Let's take Nader for example. He was a champion of the middle class. Higher minimum wage, more worker rights, raising taxes on the rich. And he got some people talking about this stuff. It's part of what made me vote for him in 2000. But his presence spoiled the election for Gore which allowed Bush to very narrowly get elected. What was the result? Stagnant minimum wages, an erosion of worker rights, and lower taxes on the rich. Was this a good trade-off for the things I care about? Absolutely not.
And I've been to many Bernie rallies. I've passed out Bernie buttons and Bernie bumper stickers. I even had a personal lunch with him the summer before he decided to run. I've been a Bernie fan for many years. I will caucus hard for him. But if he doesn't get in, I'll vote Hillary. And I'm sure Bernie will as well. I'll work hard to get the person I want elected. But if they don't get in the general, I also won't shoot myself in the foot by helping the other party, which I really disagree with, get in.