I do have a team. That team is the Democrats. Yet, like you, my identity is not tied up in the Democratic party, and I want to see the world as it is and use my best judgment. I firmly reject that premise that you are ‘above me’ because you have not chosen a team.
The reason I have the team I do is because all feasible outcomes, both this year and in the foreseeable future, will involve me supporting the Democrats over the Republicans. They are more consistent with my POV in a number of areas: taxes, spending, urban development, foreign adventurism, gay rights, abortion, etc.
It’s not, strictly speaking, impossible that the Republicans will have a contested convention and emerge having nominated a Cory Booker/Julian Castro ticket, at which point I can certainly re-evaluate my team choice. But until there’s some sort of significant political realignment, I see no character flaw in having chosen the team that I have.
This is not a given. If Stein actually manages to shave a considerable percentage of votes off from the left, Democrats may very reasonably cement themselves as a centrist party, as that becomes the unoccupied space. If progressives - which I see you don’t identify as, but most Sanders supporters do - want to influence the Democratic party, their best bet is to be in the party, and do the hard work of organizing, attending countless caucuses, party meetings at the county level, etc. In other words, join a team, and try to make that team more like themselves. Voting every four years isn’t going to cut it.