The Republicans know you're not going to switch to Democrat. And they know despite everything, this is a two-party system, other parties just don't have the clout to win. Bernie got in because despite him being "Independent" he has to become a "temporary Democrat" to run so he gets party backing.
The Republicans who sold us out know unless we just want to throw our vote away we have to vote for them or a Democrat and they know we aren't ever voting Democrat. there just aren't going to be enough of us switching to a 3rd party candidate to scare them.
Not saying don't do it, I definitely am going unaffiliated but I wonder how much they will care.
We could easily start a new party or become the independent party if we were organized. The key to all this is organizing. Until that happens, we're reactionary playing into the hands of the ones that dare.