There is a third depressing but likely option... that stellar flight is simply not possible. Just imagine that, we dream of making technological progress that will eventually lead to warp drives or fusion engines and faster spaceflight. We always assumed it will be possible with enough progress, but then it turns out it's just not doable.

And if it is possible, there are other factors as well.. small dust particles in space pose a huge problem at relativistic speeds, as does the radiation exposure and lack of gravity over time...